Heme acquisition in the parasitic filarial nematode Brugia malayi.

PubMed

Luck, Ashley N; Yuan, Xiaojing; Voronin, Denis; Slatko, Barton E; Hamza, Iqbal; Foster, Jeremy M

2016-10-01

Nematodes lack a heme biosynthetic pathway and must acquire heme from exogenous sources. Given the indispensable role of heme, this auxotrophy may be exploited to develop drugs that interfere with heme uptake in parasites. Although multiple heme-responsive genes (HRGs) have been characterized within the free-living nematode Caenorhabditis elegans, we have undertaken the first study of heme transport in Brugia malayi, a causative agent of lymphatic filariasis. Through functional assays in yeast, as well as heme analog, RNAi, and transcriptomic experiments, we have shown that the heme transporter B. malayi HRG-1 (BmHRG-1) is indeed functional in B. malayi In addition, BmHRG-1 localizes both to the endocytic compartments and cell membrane when expressed in yeast cells. Transcriptomic sequencing revealed that BmHRG-1, BmHRG-2, and BmMRP-5 (all orthologs of HRGs in C. elegans) are down-regulated in heme-treated B. malayi, as compared to non-heme-treated control worms. Likely because of short gene lengths, multiple exons, other HRGs in B. malayi (BmHRG-3-6) remain unidentified. Although the precise mechanisms of heme homeostasis in a nematode with the ability to acquire heme remains unknown, this study clearly demonstrates that the filarial nematode B. malayi is capable of transporting exogenous heme.-Luck, A. N., Yuan, X., Voronin, D., Slatko, B. E., Hamza, I., Foster, J. M. Heme acquisition in the parasitic filarial nematode Brugia malayi. © The Author(s).

Heme acquisition in the parasitic filarial nematode Brugia malayi

PubMed Central

Luck, Ashley N.; Yuan, Xiaojing; Voronin, Denis; Slatko, Barton E.; Hamza, Iqbal; Foster, Jeremy M.

2016-01-01

Nematodes lack a heme biosynthetic pathway and must acquire heme from exogenous sources. Given the indispensable role of heme, this auxotrophy may be exploited to develop drugs that interfere with heme uptake in parasites. Although multiple heme-responsive genes (HRGs) have been characterized within the free-living nematode Caenorhabditis elegans, we have undertaken the first study of heme transport in Brugia malayi, a causative agent of lymphatic filariasis. Through functional assays in yeast, as well as heme analog, RNAi, and transcriptomic experiments, we have shown that the heme transporter B. malayi HRG-1 (BmHRG-1) is indeed functional in B. malayi. In addition, BmHRG-1 localizes both to the endocytic compartments and cell membrane when expressed in yeast cells. Transcriptomic sequencing revealed that BmHRG-1, BmHRG-2, and BmMRP-5 (all orthologs of HRGs in C. elegans) are down-regulated in heme-treated B. malayi, as compared to non–heme-treated control worms. Likely because of short gene lengths, multiple exons, other HRGs in B. malayi (BmHRG-3–6) remain unidentified. Although the precise mechanisms of heme homeostasis in a nematode with the ability to acquire heme remains unknown, this study clearly demonstrates that the filarial nematode B. malayi is capable of transporting exogenous heme.—Luck, A. N., Yuan, X., Voronin, D., Slatko, B. E., Hamza, I., Foster, J. M. Heme acquisition in the parasitic filarial nematode Brugia malayi. PMID:27363426

How do humans affect wildlife nematodes?

USGS Publications Warehouse

Weinstein, Sara B.; Lafferty, Kevin D.

2015-01-01

Human actions can affect wildlife and their nematode parasites. Species introductions and human-facilitated range expansions can create new host–parasite interactions. Novel hosts can introduce parasites and have the potential to both amplify and dilute nematode transmission. Furthermore, humans can alter existing nematode dynamics by changing host densities and the abiotic conditions that affect larval parasite survival. Human impacts on wildlife might impair parasites by reducing the abundance of their hosts; however, domestic animal production and complex life cycles can maintain transmission even when wildlife becomes rare. Although wildlife nematodes have many possible responses to human actions, understanding host and parasite natural history, and the mechanisms behind the changing disease dynamics might improve disease control in the few cases where nematode parasitism impacts wildlife.

Natural genetic and induced plant resistance, as a control strategy to plant-parasitic nematodes alternative to pesticides.

PubMed

Molinari, Sergio

2011-03-01

Plant-parasitic nematodes are pests of a wide range of economically important crops, causing severe losses to agriculture. Natural genetic resistance of plants is expected to be a valid solution of the many problems nematodes cause all over the world. Progress in resistance applications is particularly important for the less-developed countries of tropical and subtropical regions, since use of resistant cultivars may be the only possible and economically feasible control strategy in those farming systems. Resistance is being considered of particular importance also in modern high-input production systems of developed countries, as the customary reliance on chemical nematicides has been restricted or has come to an end. This review briefly describes the genetic bases of resistance to nematodes in plants and focuses on the chances and problems of its exploitation as a key element in an integrated management program. Much space is dedicated to the major problem of resistance durability, in that the intensive use of resistant cultivars is likely to increasingly induce the selection of virulent populations able to "break" the resistance. Protocols of pest-host suitability are described, as bioassays are being used to evaluate local nematode populations in their potential to be selected on resistant germplasm and endanger resistant crops. The recent progress in using robust and durable resistances against nematodes as an efficient method for growers in vegetable cropping systems is reported, as well as the possible use of chemicals that do not show any unfavorable impact on environment, to induce in plants resistance against plant-parasitic nematodes.

Aggregative group behavior in insect parasitic nematode dispersal.

PubMed

Shapiro-Ilan, David I; Lewis, Edwin E; Schliekelman, Paul

2014-01-01

Movement behavior of foraging animals is critical to the determination of their spatial ecology and success in exploiting resources. Individuals sometimes gain advantages by foraging in groups to increase their efficiency in garnering these resources. Group movement behavior has been studied in various vertebrates. In this study we explored the propensity for innate group movement behavior among insect parasitic nematodes. Given that entomopathogenic nematodes benefit from group attack and infection, we hypothesised that the populations would tend to move in aggregate in the absence of extrinsic cues. Movement patterns of entomopathogenic nematodes in sand were investigated when nematodes were applied to a specific locus or when the nematodes emerged naturally from infected insect hosts; six nematode species in two genera were tested (Heterorhabditis bacteriophora, Heterorhabditis indica, Steinernema carpocapsae, Steinernema feltiae, Steinernema glaseri and Steinernema riobrave). Nematodes were applied in aqueous suspension via filter paper discs or in infected insect host cadavers (to mimic emergence in nature). We discovered that nematode dispersal resulted in an aggregated pattern rather than a random or uniform distribution; the only exception was S. glaseri when emerging directly from infected hosts. The group movement may have been continuous from the point of origin, or it may have been triggered by a propensity to aggregate after a short period of random movement. To our knowledge, this is the first report of group movement behavior in parasitic nematodes in the absence of external stimuli (e.g., without an insect or other apparent biotic or abiotic cue). These findings have implications for nematode spatial distribution and suggest that group behavior is involved in nematode foraging. Published by Elsevier Ltd.

Naturally induced secretions of the potato cyst nematode co-stimulate the proliferation of both tobacco leaf protoplasts and human peripheral blood mononuclear cells.

PubMed

Goverse, A; Rouppe van der Voort, J; Roppe van der Voort, C; Kavelaars, A; Smant, G; Schots, A; Bakker, J; Helder, J

1999-10-01

Naturally induced secretions from infective juveniles of the potato cyst nematode Globodera rostochiensis co-stimulate the proliferation of tobacco leaf protoplasts in the presence of the synthetic phytohormones alpha-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP). With the use of a protoplast-based bioassay, a low-molecular-weight peptide(s) (< 3 kDa) was shown to be responsible for the observed effect. This mitogenic oligopeptide(s) is functionally dissimilar to auxin and cytokinin and, in addition, it does not change the sensitivity of the protoplasts toward these phytohormones. In combination with the mitogen phytohemagglutinin (PHA), cyst nematode secretions also co-stimulated mitogenesis in human peripheral blood mononuclear cells (PBMC). The stimulation of plant cells isolated from nontarget tissue--these nematodes normally invade the roots of potato plants--suggests the activation of a general signal transduction mechanism(s) by an oligopeptide(s) secreted by the nematode. Whether a similar oligopeptide-induced mechanism underlies human PBMC activation remains to be investigated. Reactivation of the cell cycle is a crucial event in feeding cell formation by cyst nematodes. The secretion of a mitogenic low-molecular-weight peptide(s) by infective juveniles of the potato cyst nematode could contribute to the redifferentiation of plant cells into such a feeding cell.

Naturally acquired antibodies against Clostridium perfringens epsilon toxin in goats.

PubMed

Veschi, Josir Laine A; Bruzzone, Octavio A; Losada-Eaton, Daniela M; Dutra, Iveraldo S; Fernandez-Miyakawa, Mariano E

2008-09-15

Clostridium perfringens type D-producing epsilon toxin is a common cause of death in sheep and goats worldwide. Although anti-epsilon toxin serum antibodies have been detected in healthy non-vaccinated sheep, the information regarding naturally acquired antibodies in ruminants is scanty. The objective of the present report was to characterize the development of naturally acquired antibodies against C. perfringens epsilon toxin in goats. The levels of anti-epsilon toxin antibodies in blood serum of goat kids from two different herds were examined continuously for 14 months. Goats were not vaccinated against any clostridial disease and received heterologous colostrums from cows that were not vaccinated against any clostridial disease. During the survey one of these flocks suffered an unexpectedly severe C. perfringens type D enterotoxemia outbreak. The results showed that natural acquired antibodies against C. perfringens epsilon toxin can appear as early as 6 weeks in young goats and increase with the age without evidence of clinical disease. The enterotoxemia outbreak was coincident with a significant increase in the level of anti-epsilon toxin antibodies.

Parameters affecting plant defense pathway mediated recruitment of entomopathogenic nematodes

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes are natural enemies and effective biological control agents of subterranean insect herbivores. Interactions between her bivores, plants, and entomopathogenic nematodes are mediated by plant defense pathways that can induce release of volatiles that recruit entomopathogenic...

Potentialities of Mermithid Nematodes for the Biocontrol of Blackflies (Diptera: Simuliidae)--A Review,

DTIC Science & Technology

biocontrol agents of agricultural insect pests and medically important insect vectors. More specifically, mermithid nematodes appear to regulate natural...Mermithids comprise a family of nematodes which invariably kill/sterilize their insect host(s). These nematodes have considerable potential as

Efficacy of an ivermectin controlled-release capsule against nematode and arthropod endoparasites in sheep.

PubMed

Rehbein, S; Batty, A F; Barth, D; Visser, M; Timms, B J; Barrick, R A; Eagleson, J S

1998-03-28

Five controlled trials were conducted in Germany or in the United Kingdom, using 74 female sheep of merino or Dorset horn breeds, to evaluate the efficacy of an ivermectin controlled-release capsule against naturally acquired or induced infections of gastrointestinal nematodes, lungworms and nasal bot larvae and against incoming infections with gastrointestinal and pulmonary nematodes. Half of the animals were treated with one ivermectin controlled-release capsule that delivered ivermectin at the rate of 1.6 mg per day for 100 days while the other half remained untreated. Parasites were counted 21, 28, 35 or 56 days after administration of the capsule. The treatment was highly effective (> or = 99 per cent) against established parasites of the following species: Haemonchus contortus (adults and fourth-stage larvae), Ostertagia circumcincta, O pinnata, O trifurcata, Ostertagia species fourth-stage larvae, Trichostrongylus axei, T colubriformis, T vitrinus, Cooperia curticei, Nematodirus battus, N filicollis, Strongyloides papillosus, Chabertia ovina, Oesophagostomum venulosum, Trichuris ovis, Tr skrjabini, Dictyocaulus filaria, Protostrongylus rufescens and Oestrus ovis (larvae). The treatment prevented the establishment of the gastrointestinal nematodes H contortus, O circumcincta, T axei, T colubriformis, C curticei, N battus, N filicollis, Ch ovina, Oe vennulosum and the establishment of the lungworm D filaria by > 99 per cent compared with untreated controls (P < or = 0.01).

Strategies for transgenic nematode control in developed and developing world crops.

PubMed

Atkinson, Howard J; Lilley, Catherine J; Urwin, Peter E

2012-04-01

Nematodes cause an estimated $118b annual losses to world crops and they are not readily controlled by pesticides or other control options. For many crops natural resistance genes are unavailable to plant breeders or progress by this approach is slow. Transgenic plants can provide nematode resistance for such crops. Two approaches have been field trialled that control a wide range of nematodes by either limiting use of their dietary protein uptake from the crop or by preventing root invasion without a direct lethality. In addition, RNA interference increasingly in tandem with genomic studies is providing a range of potential resistance traits that involve no novel protein production. Transgenic resistance can be delivered by tissue specific promoters to just root tissues where most economic nematodes invade and feed rather than the harvested yield. High efficacy and durability can be provided by stacking nematode resistance traits including any that natural resistance provides. The constraints to uptake centre on market acceptance and not the availability of appropriate biotechnology. The need to deploy nematode resistance is intensifying with loss of pesticides, an increased need to protect crop profit margins and in many developing world countries where nematodes severely damage both commodity and staple crops. Copyright © 2011 Elsevier Ltd. All rights reserved.

The native microbiome of the nematode Caenorhabditis elegans: gateway to a new host-microbiome model.

PubMed

Dirksen, Philipp; Marsh, Sarah Arnaud; Braker, Ines; Heitland, Nele; Wagner, Sophia; Nakad, Rania; Mader, Sebastian; Petersen, Carola; Kowallik, Vienna; Rosenstiel, Philip; Félix, Marie-Anne; Schulenburg, Hinrich

2016-05-09

Host-microbe associations underlie many key processes of host development, immunity, and life history. Yet, none of the current research on the central model species Caenorhabditis elegans considers the worm's natural microbiome. Instead, almost all laboratories exclusively use the canonical strain N2 and derived mutants, maintained through routine bleach sterilization in monoxenic cultures with an E. coli strain as food. Here, we characterize for the first time the native microbiome of C. elegans and assess its influence on nematode life history characteristics. Nematodes sampled directly from their native habitats carry a species-rich bacterial community, dominated by Proteobacteria such as Enterobacteriaceae and members of the genera Pseudomonas, Stenotrophomonas, Ochrobactrum, and Sphingomonas. The C. elegans microbiome is distinct from that of the worm's natural environment and the congeneric species C. remanei. Exposure to a derived experimental microbiome revealed that bacterial composition is influenced by host developmental stage and genotype. These experiments also showed that the microbes enhance host fitness under standard and also stressful conditions (e.g., high temperature and either low or high osmolarity). Taking advantage of the nematode's transparency, we further demonstrate that several Proteobacteria are able to enter the C. elegans gut and that an Ochrobactrum isolate even seems to be able to persist in the intestines under stressful conditions. Moreover, three Pseudomonas isolates produce an anti-fungal effect in vitro which we show can contribute to the worm's defense against fungal pathogens in vivo. This first systematic analysis of the nematode's native microbiome reveals a species-rich bacterial community to be associated with C. elegans, which is likely of central importance for our understanding of the worm's biology. The information acquired and the microbial isolates now available for experimental work establishes C. elegans as a

Reciprocal Interactions between Nematodes and Their Microbial Environments

PubMed Central

Midha, Ankur; Schlosser, Josephine; Hartmann, Susanne

2017-01-01

Parasitic nematode infections are widespread in nature, affecting humans as well as wild, companion, and livestock animals. Most parasitic nematodes inhabit the intestines of their hosts living in close contact with the intestinal microbiota. Many species also have tissue migratory life stages in the absence of severe systemic inflammation of the host. Despite the close coexistence of helminths with numerous microbes, little is known concerning these interactions. While the environmental niche is considerably different, the free-living nematode Caenorhabditis elegans (C. elegans) is also found amongst a diverse microbiota, albeit on decaying organic matter. As a very well characterized model organism that has been intensively studied for several decades, C. elegans interactions with bacteria are much more deeply understood than those of their parasitic counterparts. The enormous breadth of understanding achieved by the C. elegans research community continues to inform many aspects of nematode parasitology. Here, we summarize what is known regarding parasitic nematode-bacterial interactions while comparing and contrasting this with information from work in C. elegans. This review highlights findings concerning responses to bacterial stimuli, antimicrobial peptides, and the reciprocal influences between nematodes and their environmental bacteria. Furthermore, the microbiota of nematodes as well as alterations in the intestinal microbiota of mammalian hosts by helminth infections are discussed. PMID:28497029

Reciprocal Interactions between Nematodes and Their Microbial Environments.

PubMed

Midha, Ankur; Schlosser, Josephine; Hartmann, Susanne

2017-01-01

Parasitic nematode infections are widespread in nature, affecting humans as well as wild, companion, and livestock animals. Most parasitic nematodes inhabit the intestines of their hosts living in close contact with the intestinal microbiota. Many species also have tissue migratory life stages in the absence of severe systemic inflammation of the host. Despite the close coexistence of helminths with numerous microbes, little is known concerning these interactions. While the environmental niche is considerably different, the free-living nematode Caenorhabditis elegans ( C. elegans ) is also found amongst a diverse microbiota, albeit on decaying organic matter. As a very well characterized model organism that has been intensively studied for several decades, C. elegans interactions with bacteria are much more deeply understood than those of their parasitic counterparts. The enormous breadth of understanding achieved by the C. elegans research community continues to inform many aspects of nematode parasitology. Here, we summarize what is known regarding parasitic nematode-bacterial interactions while comparing and contrasting this with information from work in C. elegans . This review highlights findings concerning responses to bacterial stimuli, antimicrobial peptides, and the reciprocal influences between nematodes and their environmental bacteria. Furthermore, the microbiota of nematodes as well as alterations in the intestinal microbiota of mammalian hosts by helminth infections are discussed.

Transgenic Strategies for Enhancement of Nematode Resistance in Plants

PubMed Central

Ali, Muhammad A.; Azeem, Farrukh; Abbas, Amjad; Joyia, Faiz A.; Li, Hongjie; Dababat, Abdelfattah A.

2017-01-01

Plant parasitic nematodes (PPNs) are obligate biotrophic parasites causing serious damage and reduction in crop yields. Several economically important genera parasitize various crop plants. The root-knot, root lesion, and cyst nematodes are the three most economically damaging genera of PPNs on crops within the family Heteroderidae. It is very important to devise various management strategies against PPNs in economically important crop plants. Genetic engineering has proven a promising tool for the development of biotic and abiotic stress tolerance in crop plants. Additionally, the genetic engineering leading to transgenic plants harboring nematode resistance genes has demonstrated its significance in the field of plant nematology. Here, we have discussed the use of genetic engineering for the development of nematode resistance in plants. This review article also provides a detailed account of transgenic strategies for the resistance against PPNs. The strategies include natural resistance genes, cloning of proteinase inhibitor coding genes, anti-nematodal proteins and use of RNA interference to suppress nematode effectors. Furthermore, the manipulation of expression levels of genes induced and suppressed by nematodes has also been suggested as an innovative approach for inducing nematode resistance in plants. The information in this article will provide an array of possibilities to engineer resistance against PPNs in different crop plants. PMID:28536595

Transgenic Strategies for Enhancement of Nematode Resistance in Plants.

PubMed

Ali, Muhammad A; Azeem, Farrukh; Abbas, Amjad; Joyia, Faiz A; Li, Hongjie; Dababat, Abdelfattah A

2017-01-01

Plant parasitic nematodes (PPNs) are obligate biotrophic parasites causing serious damage and reduction in crop yields. Several economically important genera parasitize various crop plants. The root-knot, root lesion, and cyst nematodes are the three most economically damaging genera of PPNs on crops within the family Heteroderidae. It is very important to devise various management strategies against PPNs in economically important crop plants. Genetic engineering has proven a promising tool for the development of biotic and abiotic stress tolerance in crop plants. Additionally, the genetic engineering leading to transgenic plants harboring nematode resistance genes has demonstrated its significance in the field of plant nematology. Here, we have discussed the use of genetic engineering for the development of nematode resistance in plants. This review article also provides a detailed account of transgenic strategies for the resistance against PPNs. The strategies include natural resistance genes, cloning of proteinase inhibitor coding genes, anti-nematodal proteins and use of RNA interference to suppress nematode effectors. Furthermore, the manipulation of expression levels of genes induced and suppressed by nematodes has also been suggested as an innovative approach for inducing nematode resistance in plants. The information in this article will provide an array of possibilities to engineer resistance against PPNs in different crop plants.

United States Department of Agriculture-Agricultural Research Service research programs on microbes for management of plant-parasitic nematodes.

PubMed

Meyer, Susan L F

2003-01-01

Restrictions on the use of conventional nematicides have increased the need for new methods of managing plant-parasitic nematodes. Consequently, nematode-antagonistic microbes, and active compounds produced by such organisms, are being explored as potential additions to management practices. Programs in this area at the USDA Agricultural Research Service investigate applied biocontrol agents, naturally occurring beneficial soil microbes and natural compounds. Specific research topics include use of plant growth-promoting rhizobacteria and cultural practices for management of root-knot and ring nematodes, determination of management strategies that enhance activity of naturally occurring Pasteuria species (bacterial obligate parasites of nematodes), studies on interactions between biocontrol bacteria and bacterial-feeding nematodes, and screening of microbes for compounds active against plant-parasitic nematodes. Some studies involve biocontrol agents that are active against nematodes and soil-borne plant-pathogenic fungi, or combinations of beneficial bacteria and fungi, to manage a spectrum of plant diseases or to increase efficacy over a broader range of environmental conditions. Effective methods or agents identified in the research programs are investigated as additions to existing management systems for plant-parasitic nematodes.

A bias for the natural? Children's beliefs about traits acquired through effort, bribes, or medicine.

PubMed

Lockhart, Kristi L; Keil, Frank C; Aw, Justine

2013-09-01

Three studies compared beliefs about natural and late blooming positive traits with those acquired through personal effort, extrinsic rewards or medicine. Young children (5-6 years), older children (8-13 years), and adults all showed a strong bias for natural and late blooming traits over acquired traits. All age groups, except 8- to 10-year-olds, treated natural and late-blooming traits as fixed essences that would persist over time and under challenging conditions. Older children and adults viewed traits acquired by intrinsic effort as more similar to natural and late-blooming traits than those acquired through bribes or medicine, suggesting that intrinsic effort itself comes to be seen as a more natural mechanism of change. A bias for the natural may therefore be an early emerging way of evaluating others that is reinforced by the ambient culture and becomes stronger with increasing age. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Nematode-Trapping Fungi.

PubMed

Jiang, Xiangzhi; Xiang, Meichun; Liu, Xingzhong

2017-01-01

Nematode-trapping fungi are a unique and intriguing group of carnivorous microorganisms that can trap and digest nematodes by means of specialized trapping structures. They can develop diverse trapping devices, such as adhesive hyphae, adhesive knobs, adhesive networks, constricting rings, and nonconstricting rings. Nematode-trapping fungi have been found in all regions of the world, from the tropics to Antarctica, from terrestrial to aquatic ecosystems. They play an important ecological role in regulating nematode dynamics in soil. Molecular phylogenetic studies have shown that the majority of nematode-trapping fungi belong to a monophyletic group in the order Orbiliales (Ascomycota). Nematode-trapping fungi serve as an excellent model system for understanding fungal evolution and interaction between fungi and nematodes. With the development of molecular techniques and genome sequencing, their evolutionary origins and divergence, and the mechanisms underlying fungus-nematode interactions have been well studied. In recent decades, an increasing concern about the environmental hazards of using chemical nematicides has led to the application of these biological control agents as a rapidly developing component of crop protection.

Natural variation in Pristionchus pacificus dauer formation reveals cross-preference rather than self-preference of nematode dauer pheromones

PubMed Central

Mayer, Melanie G.; Sommer, Ralf J.

2011-01-01

Many free-living nematodes, including the laboratory model organisms Caenorhabditis elegans and Pristionchus pacificus, have a choice between direct and indirect development, representing an important case of phenotypic plasticity. Under harsh environmental conditions, these nematodes form dauer larvae, which arrest development, show high resistance to environmental stress and constitute a dispersal stage. Pristionchus pacificus occurs in a strong association with scarab beetles in the wild and remains in the dauer stage on the living beetle. Here, we explored the circumstances under which P. pacificus enters and exits the dauer stage by using a natural variation approach. The analysis of survival, recovery and fitness after dauer exit of eight P. pacificus strains revealed that dauer larvae can survive for up to 1 year under experimental conditions. In a second experiment, we isolated dauer pheromones from 16 P. pacificus strains, and tested for natural variation in pheromone production and sensitivity in cross-reactivity assays. Surprisingly, 13 of the 16 strains produce a pheromone that induces the highest dauer formation in individuals of other genotypes. These results argue against a simple adaptation model for natural variation in dauer formation and suggest that strains may have evolved to induce dauer formation precociously in other strains in order to reduce the fitness of these strains. We therefore discuss intraspecific competition among genotypes as a previously unconsidered aspect of dauer formation. PMID:21307052

Reflections on Plant and Soil Nematode Ecology: Past, Present and Future

PubMed Central

Ferris, Howard; Griffiths, Bryan S.; Porazinska, Dorota L.; Powers, Thomas O.; Wang, Koon-Hui; Tenuta, Mario

2012-01-01

The purpose of this review is to highlight key developments in nematode ecology from its beginnings to where it stands today as a discipline within nematology. Emerging areas of research appear to be driven by crop production constraints, environmental health concerns, and advances in technology. In contrast to past ecological studies which mainly focused on management of plant-parasitic nematodes, current studies reflect differential sensitivity of nematode faunae. These differences, identified in both aquatic and terrestrial environments include response to stressors, environmental conditions, and management practices. Methodological advances will continue to influence the role nematodes have in addressing the nature of interactions between organisms, and of organisms with their environments. In particular, the C. elegans genetic model, nematode faunal analysis and nematode metagenetic analysis can be used by ecologists generally and not restricted to nematologists. PMID:23482864

Smart Parasitic Nematodes Use Multifaceted Strategies to Parasitize Plants

PubMed Central

Ali, Muhammad A.; Azeem, Farrukh; Li, Hongjie; Bohlmann, Holger

2017-01-01

Nematodes are omnipresent in nature including many species which are parasitic to plants and cause enormous economic losses in various crops. During the process of parasitism, sedentary phytonematodes use their stylet to secrete effector proteins into the plant cells to induce the development of specialized feeding structures. These effectors are used by the nematodes to develop compatible interactions with plants, partly by mimicking the expression of host genes. Intensive research is going on to investigate the molecular function of these effector proteins in the plants. In this review, we have summarized which physiological and molecular changes occur when endoparasitic nematodes invade the plant roots and how they develop a successful interaction with plants using the effector proteins. We have also mentioned the host genes which are induced by the nematodes for a compatible interaction. Additionally, we discuss how nematodes modulate the reactive oxygen species (ROS) and RNA silencing pathways in addition to post-translational modifications in their own favor for successful parasitism in plants. PMID:29046680

Smart Parasitic Nematodes Use Multifaceted Strategies to Parasitize Plants.

PubMed

Ali, Muhammad A; Azeem, Farrukh; Li, Hongjie; Bohlmann, Holger

2017-01-01

Nematodes are omnipresent in nature including many species which are parasitic to plants and cause enormous economic losses in various crops. During the process of parasitism, sedentary phytonematodes use their stylet to secrete effector proteins into the plant cells to induce the development of specialized feeding structures. These effectors are used by the nematodes to develop compatible interactions with plants, partly by mimicking the expression of host genes. Intensive research is going on to investigate the molecular function of these effector proteins in the plants. In this review, we have summarized which physiological and molecular changes occur when endoparasitic nematodes invade the plant roots and how they develop a successful interaction with plants using the effector proteins. We have also mentioned the host genes which are induced by the nematodes for a compatible interaction. Additionally, we discuss how nematodes modulate the reactive oxygen species (ROS) and RNA silencing pathways in addition to post-translational modifications in their own favor for successful parasitism in plants.

Localization of Haemophilus ducreyi in naturally acquired chancroidal ulcers.

PubMed

Bauer, Margaret E; Townsend, Carisa A; Ronald, Allan R; Spinola, Stanley M

2006-08-01

Haemophilus ducreyi causes the sexually transmitted genital ulcer disease chancroid. In human inoculation experiments, bacteria colocalize with neutrophils and macrophages but remain extracellular. The organism also colocalizes with collagen and fibrin but not with keratinocytes, fibroblasts, laminin, or fibronectin. These relationships are established by 48 h postinoculation and persist through the pustular stage of disease. To extend these observations to the ulcerative stage of disease, and to compare results in the human model with those of natural disease, we obtained biopsies from patients with naturally acquired chancroid. All ulcers were culture positive for H. ducreyi and histologically very similar to pustules from the human model. Staining with H. ducreyi-specific monoclonal antibodies demonstrated H. ducreyi within 5 biopsies. The organism was chiefly found within the granulocytic infiltrate of the ulcer. Dual staining for H. ducreyi and eukaryotic tissue components showed that H. ducreyi colocalized with neutrophils and fibrin at the ulcerative stage of disease. No bacteria were associated with keratinocytes, fibroblasts, or collagen. Overall, these findings are consistent with results from the human model. This is the first reported study to localize bacteria specifically identified as H. ducreyi within naturally acquired chancroid.

Nematode burdens of pastured cattle treated once at turnout with eprinomectin extended-release injection.

PubMed

Rehbein, S; Baggott, D G; Johnson, E G; Kunkle, B N; Yazwinski, T A; Yoon, S; Cramer, L G; Soll, M D

2013-03-01

The efficacy of eprinomectin in an extended-release injection (ERI) formulation was evaluated against infections with third-stage larvae or eggs of gastrointestinal and pulmonary nematodes in cattle under 120-day natural challenge conditions in a series of five studies conducted in the USA (three studies) and in Europe (two studies). For each study, 30 nematode-free (four studies) or 30 cattle harboring naturally acquired nematode infections (one study) were included. The cattle were of various breeds or crosses, weighed 107.5-273 kg prior to treatment and aged approximately 4-11 months. For each study, animals were blocked based on pre-treatment bodyweight and then randomly allocated to treatment: ERI vehicle (control) at 1 mL/50 kg bodyweight or Eprinomectin 5% (w/v) ERI at 1 mL/50 kg bodyweight (1.0 mg eprinomectin/kg) for a total of 15 and 15 animals in each group. Treatments were administered once on Day 0 by subcutaneous injection in front of the shoulder. In each study, all animals grazed one naturally contaminated pasture for 120 days. At regular intervals during the studies, fecal samples from all cattle were examined for nematode egg and larval counts. In four studies pairs of tracer cattle were used to monitor pasture infectivity at 28-day intervals before and/or during the grazing period. All calves were weighed before turnout onto pasture and at regular intervals until housing on Day 120. For parasite recovery, all study animals were humanely euthanized 27-30 days after removal from pasture. Cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer strongylid eggs (≤1 egg per gram; egg count reduction≥94%) than the control cattle and zero lungworm larvae at each post-treatment time point. At euthanasia, cattle treated with Eprinomectin ERI had significantly (p<0.05) fewer of the following nematodes than the ERI vehicle-treated (control) cattle with overall reduction of nematode counts by >92%: Dictyocaulus viviparus (adults and fourth

Endosymbiont-based immunity in Drosophila melanogaster against parasitic nematode infection.

PubMed

Yadav, Shruti; Frazer, Joanna; Banga, Ashima; Pruitt, Katherine; Harsh, Sneh; Jaenike, John; Eleftherianos, Ioannis

2018-01-01

Associations between endosymbiotic bacteria and their hosts represent a complex ecosystem within organisms ranging from humans to protozoa. Drosophila species are known to naturally harbor Wolbachia and Spiroplasma endosymbionts, which play a protective role against certain microbial infections. Here, we investigated whether the presence or absence of endosymbionts affects the immune response of Drosophila melanogaster larvae to infection by Steinernema carpocapsae nematodes carrying or lacking their mutualistic Gram-negative bacteria Xenorhabdus nematophila (symbiotic or axenic nematodes, respectively). We find that the presence of Wolbachia alone or together with Spiroplasma promotes the survival of larvae in response to infection with S. carpocapsae symbiotic nematodes, but not against axenic nematodes. We also find that Wolbachia numbers are reduced in Spiroplasma-free larvae infected with axenic compared to symbiotic nematodes, and they are also reduced in Spiroplasma-containing compared to Spiroplasma-free larvae infected with axenic nematodes. We further show that S. carpocapsae axenic nematode infection induces the Toll pathway in the absence of Wolbachia, and that symbiotic nematode infection leads to increased phenoloxidase activity in D. melanogaster larvae devoid of endosymbionts. Finally, infection with either type of nematode alters the metabolic status and the fat body lipid droplet size in D. melanogaster larvae containing only Wolbachia or both endosymbionts. Our results suggest an interaction between Wolbachia endosymbionts with the immune response of D. melanogaster against infection with the entomopathogenic nematodes S. carpocapsae. Results from this study indicate a complex interplay between insect hosts, endosymbiotic microbes and pathogenic organisms.

Variability in the intensity of nematode larvae from gastrointestinal tissues of a natural herbivore.

PubMed

van Kuren, Andrew T; Boag, Brian; Hruban, Emilie; Cattadori, Isabella M

2013-04-01

The migration of infective nematode larvae into the tissues of their hosts has been proposed as a mechanism of reducing larval mortality and increase parasite lifetime reproductive success. Given that individual hosts differ in the level of exposure, strength of immune response and physiological conditions we may expect the number of larvae in tissue to vary both between and within hosts. We used 2 gastrointestinal nematode species common in the European rabbit (Oryctolagus cuniculus) and examined how the number of larvae in the tissue changed with the immune response, parasite intensity-dependent constraints in the lumen and seasonal weather factors, in rabbits of different age, sex and breeding status. For both nematode species, larvae from the gastrointestinal tissue exhibited strong seasonal and host age-related patterns with fewer larvae recovered in summer compared to winter and more in adults than in juveniles. The number of larvae of the 2 nematodes was positively associated with intensity of parasite infection in the lumen and antibody responses while it was negatively related with air temperature and rainfall. Host sex, reproductive status and co-infection with the second parasite species contributed to increase variability between hosts. We concluded that heterogeneities in host conditions are a significant cause of variability of larval abundance in the gastrointestinal tissues. These findings can have important consequences for the dynamics of nematode infections and how parasite's life-history strategies adjust to host changes.

Outcrossing and crossbreeding recovers deteriorated traits in laboratory cultured Steinernema carpocapsae nematodes

PubMed Central

Chaston, John M.; Dillman, Adler R.; Shapiro-Ilan, David I.; Bilgrami, Anwar L.; Gaugler, Randy; Hopper, Keith R.; Adams, Byron J.

2011-01-01

The nematode Steinernema carpocapsae infects and kills many pest insects in agroecosystems and is commonly used in biocontrol of these pests. Growth of the nematodes prior to distribution for biocontrol commonly results in deterioration of traits that are essential for nematode persistence in field applications. To better understand the mechanisms underlying trait deterioration of the efficacy of natural parasitism in entomopathogenic nematodes, we explored the maintenance of fitness related traits including reproductive capacity, heat tolerance, virulence to insects and `tail standing' (formerly called nictation) among laboratory-cultured lines derived from natural, randomly mating populations of S. carpocapsae. Laboratory cultured nematode lines with fitness-related trait values below wild-type levels regained wild-type levels of reproductive and heat tolerance traits when outcrossed with a non-deteriorated line, while virulence and `tail standing' did not deteriorate in our experiments. Crossbreeding two trait-deteriorated lines with each other also resulted in restoration of trait means to wild-type levels in most crossbred lines. Our results implicate inbreeding depression as the primary cause of trait deterioration in the laboratory cultured S. carpocapsae. We further suggest the possibility of creating inbred lines purged of deleterious alleles as founders in commercial nematode growth. PMID:21447341

Outcrossing and crossbreeding recovers deteriorated traits in laboratory cultured Steinernema carpocapsae nematodes.

PubMed

Chaston, John M; Dillman, Adler R; Shapiro-Ilan, David I; Bilgrami, Anwar L; Gaugler, Randy; Hopper, Keith R; Adams, Byron J

2011-06-01

The nematode Steinernema carpocapsae infects and kills many pest insects in agro-ecosystems and is commonly used in biocontrol of these pests. Growth of the nematodes prior to distribution for biocontrol commonly results in deterioration of traits that are essential for nematode persistence in field applications. To better understand the mechanisms underlying trait deterioration of the efficacy of natural parasitism in entomopathogenic nematodes, we explored the maintenance of fitness related traits including reproductive capacity, heat tolerance, virulence to insects and 'tail standing' (formerly called nictation) among laboratory-cultured lines derived from natural, randomly mating populations of S. carpocapsae. Laboratory cultured nematode lines with fitness-related trait values below wild-type levels regained wild-type levels of reproductive and heat tolerance traits when outcrossed with a non-deteriorated line, while virulence and 'tail standing' did not deteriorate in our experiments. Crossbreeding two trait-deteriorated lines with each other also resulted in restoration of trait means to wild-type levels in most crossbred lines. Our results implicate inbreeding depression as the primary cause of trait deterioration in the laboratory cultured S. carpocapsae. We further suggest the possibility of creating inbred lines purged of deleterious alleles as founders in commercial nematode growth. Copyright © 2011 Australian Society for Parasitology Inc. All rights reserved.

Natural variation in dauer pheromone production and sensing supports intraspecific competition in nematodes.

PubMed

Bose, Neelanjan; Meyer, Jan M; Yim, Joshua J; Mayer, Melanie G; Markov, Gabriel V; Ogawa, Akira; Schroeder, Frank C; Sommer, Ralf J

2014-07-07

Dauer formation, a major nematode survival strategy, represents a model for small-molecule regulation of metazoan development [1-10]. Free-living nematodes excrete dauer-inducing pheromones that have been assumed to target conspecifics of the same genotype [9, 11]. However, recent studies in Pristionchus pacificus revealed that the dauer pheromone of some strains affects conspecifics of other genotypes more strongly than individuals of the same genotype [12]. To elucidate the mechanistic basis for this intriguing cross-preference, we compared six P. pacificus wild isolates to determine the chemical composition of their dauer-inducing metabolomes and responses to individual pheromone components. We found that these isolates produce dauer pheromone blends of different composition and respond differently to individual pheromone components. Strikingly, there is no correlation between production of and dauer response to a specific compound in individual strains. Specifically, pheromone components that are abundantly produced by one genotype induce dauer formation in other genotypes, but not necessarily in the abundant producer. Furthermore, some genotypes respond to pheromone components they do not produce themselves. These results support a model of intraspecific competition in nematode dauer formation. Indeed, we observed intraspecific competition among sympatric strains in a novel experimental assay, suggesting a new role of small molecules in nematode ecology. Copyright © 2014 Elsevier Ltd. All rights reserved.

Natural variation in Pristionchus pacificus dauer formation reveals cross-preference rather than self-preference of nematode dauer pheromones.

PubMed

Mayer, Melanie G; Sommer, Ralf J

2011-09-22

Many free-living nematodes, including the laboratory model organisms Caenorhabditis elegans and Pristionchus pacificus, have a choice between direct and indirect development, representing an important case of phenotypic plasticity. Under harsh environmental conditions, these nematodes form dauer larvae, which arrest development, show high resistance to environmental stress and constitute a dispersal stage. Pristionchus pacificus occurs in a strong association with scarab beetles in the wild and remains in the dauer stage on the living beetle. Here, we explored the circumstances under which P. pacificus enters and exits the dauer stage by using a natural variation approach. The analysis of survival, recovery and fitness after dauer exit of eight P. pacificus strains revealed that dauer larvae can survive for up to 1 year under experimental conditions. In a second experiment, we isolated dauer pheromones from 16 P. pacificus strains, and tested for natural variation in pheromone production and sensitivity in cross-reactivity assays. Surprisingly, 13 of the 16 strains produce a pheromone that induces the highest dauer formation in individuals of other genotypes. These results argue against a simple adaptation model for natural variation in dauer formation and suggest that strains may have evolved to induce dauer formation precociously in other strains in order to reduce the fitness of these strains. We therefore discuss intraspecific competition among genotypes as a previously unconsidered aspect of dauer formation. This journal is © 2011 The Royal Society

Endosymbiont-based immunity in Drosophila melanogaster against parasitic nematode infection

PubMed Central

Yadav, Shruti; Frazer, Joanna; Banga, Ashima; Pruitt, Katherine; Harsh, Sneh; Jaenike, John

2018-01-01

Associations between endosymbiotic bacteria and their hosts represent a complex ecosystem within organisms ranging from humans to protozoa. Drosophila species are known to naturally harbor Wolbachia and Spiroplasma endosymbionts, which play a protective role against certain microbial infections. Here, we investigated whether the presence or absence of endosymbionts affects the immune response of Drosophila melanogaster larvae to infection by Steinernema carpocapsae nematodes carrying or lacking their mutualistic Gram-negative bacteria Xenorhabdus nematophila (symbiotic or axenic nematodes, respectively). We find that the presence of Wolbachia alone or together with Spiroplasma promotes the survival of larvae in response to infection with S. carpocapsae symbiotic nematodes, but not against axenic nematodes. We also find that Wolbachia numbers are reduced in Spiroplasma-free larvae infected with axenic compared to symbiotic nematodes, and they are also reduced in Spiroplasma-containing compared to Spiroplasma-free larvae infected with axenic nematodes. We further show that S. carpocapsae axenic nematode infection induces the Toll pathway in the absence of Wolbachia, and that symbiotic nematode infection leads to increased phenoloxidase activity in D. melanogaster larvae devoid of endosymbionts. Finally, infection with either type of nematode alters the metabolic status and the fat body lipid droplet size in D. melanogaster larvae containing only Wolbachia or both endosymbionts. Our results suggest an interaction between Wolbachia endosymbionts with the immune response of D. melanogaster against infection with the entomopathogenic nematodes S. carpocapsae. Results from this study indicate a complex interplay between insect hosts, endosymbiotic microbes and pathogenic organisms. PMID:29466376

Predator-prey interactions of nematode-trapping fungi and nematodes: both sides of the coin.

PubMed

Vidal-Diez de Ulzurrun, Guillermo; Hsueh, Yen-Ping

2018-05-01

Nematode-trapping fungi develop complex trapping devices to capture and consume nematodes. The dynamics of these organisms is especially important given the pathogenicity of nematodes and, consequently, the potential application of nematode-trapping fungi as biocontrol agents. Furthermore, both the nematodes and nematode-trapping fungi can be easily grown in laboratories, making them a unique manipulatable predator-prey system to study their coevolution. Several different aspects of these fungi have been studied, such as their genetics and the different factors triggering trap formation. In this review, we use the nematode-trapping fungus Arthrobotrys oligospora (which forms adhesive nets) as a model to describe the trapping process. We divide this process into several stages; namely attraction, recognition, trap formation, adhesion, penetration, and digestion. We summarize the latest findings in the field and current knowledge on the interactions between nematodes and nematode-trapping fungi, representing both sides of the predator-prey interaction.

Gastrointestinal nematode species diversity in Soay sheep kept in a natural environment without active parasite control.

PubMed

Sinclair, Rona; Melville, Lynsey; Sargison, Fiona; Kenyon, Fiona; Nussey, Dan; Watt, Kathryn; Sargison, Neil

2016-08-30

Molecular methods based on ITS2 sequence analysis were used to identify strongylid parasites and describe their diversity in a management intervention and anthelmintic drug treatment-free sheep flock. Fourteen different nematode parasite species were identified in the flock and the results showed a greater level of nematode species diversity than is normally reported in managed farmed flocks, with the presence of parasites such as Bunostomum trigonocephalum, Ostertagia leptospicularis, Spiculopteragia houdemeri and Trichostrongylus retortaeformis that are considered to be absent or rare in sheep kept in comparable localities. The implied prevalences of Haemonchus contortus in lambs, and of Trichostrongylus axei in lambs, ewes and rams, were higher than those in farmed sheep kept in similar regions, while those of Teladorsagia circumcincta and Trichostrongylus vitrinus were lower. Comparison of the patterns of nematode parasite infection between the summer and autumn sampling periods showed differences from the scenarios that are commonplace in comparable managed flocks; with T. vitrinus burdens of the lambs being higher in the summer than in the winter, and Oesophagostomum venulosum being the predominant nematode species in the adult sheep during the summer, while more-or-less absent from these groups during the winter. Rams played an important role in the epidemiology of certain parasitic nematode species. The relatively non-pathogenic O. venulosum was the only parasitic nematode species to predominate in any group during the study. This preliminary characterisation of the nematode parasite burdens of sheep extensively grazed on diverse unimproved pastures will aid in the understanding of the parasitological consequences of intensive grazing management and of the manner in which modern agriculture upsets the equilibrium between parasites and their hosts. These factors must be accounted for when defining the concept of sustainable parasite control and informing

Real-time PCR as an effective technique to assess the impact of phoresy by Paenibacillus sp. bacteria on Steinernema diaprepesi nematodes in nature.

PubMed

Campos-Herrera, R; El-Borai, F E; Duncan, L W

2012-09-01

Quantitative real-time PCR (qPCR) is a powerful tool to study species of cryptic organisms in complex food webs. This technique was recently developed to detect and quantify several species of entomopathogenic nematodes (EPNs), which are widely used for biological control of insects, and some natural enemies of EPNs such as nematophagous fungi and the phoretic bacteria Paenibacillus sp. and Paenibacillus nematophilus. A drawback to the use of primers and TaqMan probes designed for Paenibacillus sp. is that the qPCR also amplified Paenibacillus thiaminolyticus and Paenibacillus popilliae, two closely related species that are not phoretically associated with EPNs. Here, we report that the detection of Paenibacillus sp. DNA in nematode samples was two orders of magnitude greater (P < 0.001) when the bacterium was added to soil together with its EPN species-specific host Steinernema diaprepesi than when it was added concomitantly with other EPNs or with species of bacterial-feeding nematodes. Just 6% of samples detected trace amounts of P. thiaminolyticus and P. popilliae exposed to the same experimental conditions. Thus, although the molecular assay detects Paenibacillus spp. DNA in nonphoretic associations, the levels are essentially background compared to the detection of Paenibacillus sp. in association with its nematode host. © 2012 Blackwell Publishing Ltd.

Cotton Cultivar Response to Root-Knot Nematodes in Two Tillage Regimes, 2008

USDA-ARS?s Scientific Manuscript database

Six cotton cultivars were evaluated for yield response to the root-knot nematode in a naturally infested field at E. V. Smith Research and Extension Center, near Shorter, Alabama. The field had a long history of root-knot nematode infestation, and the soil type was classified as a sandy loam. Plots ...

[Predacious nematode-destroying fungi].

PubMed

Czygier, M; Boguś, M I

2001-01-01

Gastrointestinal nematodes are considered a serious economic problem affecting the livestock industry around the world. Current methods of their control, relaying mainly on organic drugs, are not sustainable because parasites develop resistance to anthelmintic and bacause of increasing public concern about chemicals residues in livestock products and environment. Nematode-trapping fungi offer a very promissing, nonchemotherapeutic approach to nematode parasite control. Their potential in preventing nematodosis is well documented. In this paper we outline the present knowlege on mechanisms involved in trapping and killing nematodes by the predacious nematode-destroying fungi.

On the cultivation of free-living marine and estuarine nematodes

NASA Astrophysics Data System (ADS)

Moens, T.; Vincx, M.

1998-06-01

Although a large body of literature exists on the systematics and ecology of free-living marine and brackish-water nematodes, key questions on the nature and magnitude of interactions between nematodes and other organisms in the benthos remain unanswered. Relatively few authors have investigated live nematodes in food web studies or in experiments dealing with the nematodes’ response to a varying environment. It is mainly for the latter purpose that attempts have been made to maintain, rear and cultivate selected species. This paper describes the methodology used for the maintenance, rearing, and eventual permanent agnotobiotic cultivation of a variety of estuarine nematodes. Spot plates, where small samples of sediment or macrophyte material are inoculated on a sloppy agar layer, have been used for the purpose of maintenance and initial cultivation. Those species that reproduce on spot plates are then selected for monospecific cultivation on agar layers with different nutrient enrichments and with micro-organisms cotransferred from the spot plates as food. Mixtures of bacto and nutrient agar prepared in artificial seawater were specifically suitable for the xenic cultivation of nine bacterivorous and, when supplied with Erdschreiber nutrients, two algivorous/bacterivorous nematode species. Up to three generations of five other nematode species have been reared under laboratory conditions, and several more were kept alive and active for variable periods of time on agar. Generation times observed on spot plates for Adoncholaimus fuscus and Oncholaimus oxyuris were substantially shorter than previously published estimates and suggest a correspondingly higher predatory and scavenging potency for these and related enoplids. A procedure for the long-term storage of nematodes at -80°C with glycerol as a cryoprotectant was successfully used for Diplolaimella dievengatensis, Panagrolaimus sp. 1, and Pellioditis marina, but not for Diplolaimelloides meyli. The authors

Does scavenging extend the host range of entomopathogenic nematodes (Nematoda: Steinernematidae)?

PubMed

Půza, Vladimír; Mrácek, Zdenĕk

2010-05-01

Living and freeze-killed natural and laboratory hosts, with different susceptibility to entomopathogenic nematodes, were exposed to the larvae of Steinernema affine and Steinernema kraussei in two different experimental arenas (Eppendorf tubes, Petri dishes), and the success of the colonisation and eventual progeny production were observed. Both nematodes were able to colonise both living and dead larvae of Galleria mellonella (Lepidoptera) and adult Blatella germanica (Blattodea) even though the progeny production in dead hosts was lower on average. Living carabid beetles, Poecilus cupreus, and elaterid larvae (Coleoptera) were resistant to the infection, however, both nematodes were able to colonise and multiply in several dead P. cupreus and in a majority of dead elaterid larvae. By scavenging, EPNs can utilise cadavers of insects that are naturally resistant to EPN infection, and so broaden their host range. (c) 2010 Elsevier Inc. All rights reserved.

A Bias for the Natural? Children's Beliefs about Traits Acquired through Effort, Bribes, or Medicine

ERIC Educational Resources Information Center

Lockhart, Kristi L.; Keil, Frank C.; Aw, Justine

2013-01-01

Three studies compared beliefs about natural and late blooming positive traits with those acquired through personal effort, extrinsic rewards or medicine. Young children (5-6 years), older children (8-13 years), and adults all showed a strong bias for natural and late blooming traits over acquired traits. All age groups, except 8- to 10-year-olds,…

Parasitism of Nematodes by the Fungus Hirsutella rhossiliensis as Affected by Certain Organic Amendments

PubMed Central

Jaffee, B. A.; Ferris, H.; Stapleton, J. J.; Norton, M. V. K.; Muldoon, A. E.

1994-01-01

Experiments were conducted to determine whether the addition of organic matter to soil increased numbers of bacterivorous nematodes and parasitic activity of the nematophagous fungus Hirsutella rhossiliensis. In a peach orchard on loamy sand, parasitism of the plant-parasitic nematode Criconemella xenoplax by H. rhossiliensis was slightly suppressed and numbers of C. xenoplax were not affected by addition of 73 metric tons of composted chicken manure/ha. In the laboratory, numbers of bacterivorous nematodes (especially Acrobeloides spp.) and fungivorous nematodes increased but parasitism of nematodes by H. rhossiliensis usually decreased with addition of wheat straw or composted cow manure to a loamy sand naturally infested with H. rhossiliensis. These results do not support the hypothesis that organic amendments will enhance parasitism of nematodes by H. rhossiliensis. PMID:19279878

Natural product diversity associated with the nematode symbionts Photorhabdus and Xenorhabdus

USDA-ARS?s Scientific Manuscript database

Xenorhabdus and Photorhabdus species produce many specialized metabolites derived from non-ribosomal synthetase (NRPS) or polyketide synthase (PKS) with utilities in maintaining a complex life cycle. Both bacteria undergo a symbiosis with nematodes which is then followed by an insect pathogenic phas...

Identification and functional analysis of secreted effectors from phytoparasitic nematodes.

PubMed

Rehman, Sajid; Gupta, Vijai K; Goyal, Aakash K

2016-03-21

Plant parasitic nematodes develop an intimate and long-term feeding relationship with their host plants. They induce a multi-nucleate feeding site close to the vascular bundle in the roots of their host plant and remain sessile for the rest of their life. Nematode secretions, produced in the oesophageal glands and secreted through a hollow stylet into the host plant cytoplasm, are believed to play key role in pathogenesis. To combat these persistent pathogens, the identity and functional analysis of secreted effectors can serve as a key to devise durable control measures. In this review, we will recapitulate the knowledge over the identification and functional characterization of secreted nematode effector repertoire from phytoparasitic nematodes. Despite considerable efforts, the identity of genes encoding nematode secreted proteins has long been severely hampered because of their microscopic size, long generation time and obligate biotrophic nature. The methodologies such as bioinformatics, protein structure modeling, in situ hybridization microscopy, and protein-protein interaction have been used to identify and to attribute functions to the effectors. In addition, RNA interference (RNAi) has been instrumental to decipher the role of the genes encoding secreted effectors necessary for parasitism and genes attributed to normal development. Recent comparative and functional genomic approaches have accelerated the identification of effectors from phytoparasitic nematodes and offers opportunities to control these pathogens. Plant parasitic nematodes pose a serious threat to global food security of various economically important crops. There is a wealth of genomic and transcriptomic information available on plant parasitic nematodes and comparative genomics has identified many effectors. Bioengineering crops with dsRNA of phytonematode genes can disrupt the life cycle of parasitic nematodes and therefore holds great promise to develop resistant crops against plant

Nematodes (Rhabditida: Steinernematidae and Heterorhabditidae)

USDA-ARS?s Scientific Manuscript database

Nematodes are roundworms in the phylum Nematoda. Although most are free-living, some nematodes are parasites of plants, humans, or livestock. Entomopathogenic nematodes in the families Steinernematidae & Heterorhabditidae only parasitize insects. These nematodes are used as environmentally friend...

Anthelmintic activity of Artemisia annua L. extracts in vitro and the effect of an aqueous extract and artemisinin in sheep naturally infected with gastrointestinal nematodes

USDA-ARS?s Scientific Manuscript database

There is no effective natural alternative control for gastrointestinal nematodes (GIN) of small ruminants, with Haemonchus contortus being the most economically important GIN. Despite frequent reports of multidrug-resistant GIN, there is no new commercial anthelmintic to substitute failing ones. Alt...

Unifying the functional diversity in natural and cultivated soils using the overall body-mass distribution of nematodes.

PubMed

Mulder, Christian; Maas, Rob

2017-11-28

Sustainable use of our soils is a key goal for environmental protection. As many ecosystem services are supported belowground at different trophic levels by nematodes, soil nematodes are expected to provide objective metrics for biological quality to integrate physical and chemical soil variables. Trait measurements of body mass carried out at the individual level can in this way be correlated with environmental properties that influence the performance of soil biota. Soil samples were collected across 200 sites (4 soil types and 5 land-use types resulting in 9 combinations) during a long-term monitoring programme in the Netherlands and the functional diversity of nematode communities was investigated. Using three commonly used functional diversity indices applicable to single traits (Divergence, Evenness and Richness), a unified index of overall body-mass distribution is proposed to better illustrate the application of functional metrics as a descriptor of land use. Effects of land use and soil chemistry on the functional diversity of nematodes were demonstrated and a combination of environmental factors accounts for the low functional value of Scots Pine forest soils in comparison to the high functional value of heathland soils, whereas human factors account for the low functional and chemical values of arable fields. These findings show an unexpected high functional vulnerability of nematodes inhabiting clay-rich soils in comparison to sandy soils and support the notion that soil C:N ratio is a major driver of biodiversity. The higher the C:N ratio, the higher the overall diversity, as soil nematodes cope better with nutrient-poor agroecosystems under less intense fertilization. A trait-based way focusing on size distribution of nematodes is proposed to maintain environmental health by monitoring the overall diversity in soil biota, keeping agriculture and forestry sustainable.

A natural odor attraction between lactic acid bacteria and the nematode Caenorhabditis elegans.

PubMed

Choi, Jae Im; Yoon, Kyoung-Hye; Subbammal Kalichamy, Saraswathi; Yoon, Sung-Sik; Il Lee, Jin

2016-03-01

Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator-prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds.

A natural odor attraction between lactic acid bacteria and the nematode Caenorhabditis elegans

PubMed Central

Choi, Jae Im; Yoon, Kyoung-hye; Subbammal Kalichamy, Saraswathi; Yoon, Sung-Sik; Il Lee, Jin

2016-01-01

Animal predators can track prey using their keen sense of smell. The bacteriovorous nematode Caenorhabditis elegans employs sensitive olfactory sensory neurons that express vertebrate-like odor receptors to locate bacteria. C. elegans displays odor-related behaviors such as attraction, aversion and adaptation, but the ecological significance of these behaviors is not known. Using a combination of food microbiology and genetics, we elucidate a possible predator–prey relationship between C. elegans and lactic acid bacteria (LAB) in rotting citrus fruit. LAB produces the volatile odor diacetyl as an oxidized by-product of fermentation in the presence of citrate. We show that C. elegans is attracted to LAB when grown on citrate media or Citrus medica L, commonly known as yuzu, a citrus fruit native to East Asia, and this attraction is mediated by the diacetyl odor receptor, ODR-10. We isolated a wild LAB strain and a wild C. elegans-related nematode from rotten yuzu, and demonstrate that the wild nematode was attracted to the diacetyl produced by LAB. These results not only identify an ecological function for a C. elegans olfactory behavior, but contribute to the growing understanding of ecological relationships between the microbial and metazoan worlds. PMID:26241504

Nematode-borne plant viruses

USDA-ARS?s Scientific Manuscript database

There are 30 plant-parasitic nematode species that are known to transmit 14 plant viruses. Nematode-transmitted viruses affect a range of agriculturally important crops including grape, cherry, potato, and tomato. The nematodes that transmit viruses are found in two families, Longidoridae and Tric...

Caenorhabditis elegans Predation on Bacillus anthracis: Decontamination of Spore Contaminated Soil with Germinants and Nematodes.

PubMed

Schelkle, Bettina; Choi, Young; Baillie, Leslie W; Richter, William; Buyuk, Fatih; Celik, Elif; Wendling, Morgan; Sahin, Mitat; Gallagher, Theresa

2017-01-01

Remediation of Bacillus anthracis -contaminated soil is challenging and approaches to reduce overall spore levels in environmentally contaminated soil or after intentional release of the infectious disease agent in a safe, low-cost manner are needed. B. anthracis spores are highly resistant to biocides, but once germinated they become susceptible to traditional biocides or potentially even natural predators such as nematodes in the soil environment. Here, we describe a two-step approach to reducing B. anthracis spore load in soil during laboratory trials, whereby germinants and Caenorhabditis elegans nematodes are applied concurrently. While the application of germinants reduced B. anthracis spore load by up to four logs depending on soil type, the addition of nematodes achieved a further log reduction in spore count. These laboratory based results suggest that the combined use of nematodes and germinants could represent a promising approach for the remediation of B. anthracis spore contaminated soil. Originality-Significance Statement: This study demonstrates for the first time the successful use of environmentally friendly decontamination methods to inactivate Bacillus anthracis spores in soil using natural predators of the bacterium, nematode worms.

Feeding and the Rhodopsin Family G-Protein Coupled Receptors in Nematodes and Arthropods

PubMed Central

Cardoso, João C.R.; Félix, Rute C.; Fonseca, Vera G.; Power, Deborah M.

2012-01-01

In vertebrates, receptors of the rhodopsin G-protein coupled superfamily (GPCRs) play an important role in the regulation of feeding and energy homeostasis and are activated by peptide hormones produced in the brain-gut axis. These peptides regulate appetite and energy expenditure by promoting or inhibiting food intake. Sequence and function homologs of human GPCRs involved in feeding exist in the nematode roundworm, Caenorhabditis elegans (C. elegans), and the arthropod fruit fly, Drosophila melanogaster (D. melanogaster), suggesting that the mechanisms that regulate food intake emerged early and have been conserved during metazoan radiation. Nematodes and arthropods are the most diverse and successful animal phyla on Earth. They can survive in a vast diversity of environments and have acquired distinct life styles and feeding strategies. The aim of the present review is to investigate if this diversity has affected the evolution of invertebrate GPCRs. Homologs of the C. elegans and D. melanogaster rhodopsin receptors were characterized in the genome of other nematodes and arthropods and receptor evolution compared. With the exception of bombesin receptors (BBR) that are absent from nematodes, a similar gene complement was found. In arthropods, rhodopsin GPCR evolution is characterized by species-specific gene duplications and deletions and in nematodes by gene expansions in species with a free-living stage and gene deletions in representatives of obligate parasitic taxa. Based upon variation in GPCR gene number and potentially divergent functions within phyla we hypothesize that life style and feeding diversity practiced by nematodes and arthropods was one factor that contributed to rhodopsin GPCR gene evolution. Understanding how the regulation of food intake has evolved in invertebrates will contribute to the development of novel drugs to control nematodes and arthropods and the pests and diseases that use them as vectors. PMID:23264768

Legionella-protozoa-nematode interactions in aquatic biofilms and influence of Mip on Caenorhabditis elegans colonization.

PubMed

Rasch, Janine; Krüger, Stefanie; Fontvieille, Dominique; Ünal, Can M; Michel, Rolf; Labrosse, Aurélie; Steinert, Michael

2016-09-01

Legionella pneumophila, the causative agent of Legionnaireś disease, is naturally found in aquatic habitats. The intracellular life cycle within protozoa pre-adapted the "accidental" human pathogen to also infect human professional phagocytes like alveolar macrophages. Previous studies employing the model organism Caenorhabditis elegans suggest that also nematodes might serve as a natural host for L. pneumophila. Here, we report for the first time from a natural co-habitation of L. pneumophila and environmental nematode species within biofilms of a warm water spring. In addition, we identified the protozoan species Oxytricha bifaria, Stylonychia mytilus, Ciliophrya sp. which have never been described as potential interaction partners of L. pneumophila before. Modeling and dissection of the Legionella-protozoa-nematode interaction revealed that C. elegans ruptures Legionella-infected amoebal cells and by this means incorporate the pathogen. Further infection studies revealed that the macrophage infectivity potentiator (Mip) protein of L. pneumophila, which is known to bind collagen IV during human lung infection, promotes the colonization of the intestinal tract of L4 larvae of C. elegans and negatively influences the life span of the worms. The Mip-negative L. pneumophila mutant exhibited a 32-fold reduced colonization rate of the nematodes after 48h when compared to the wild-type strain. Taken together, these studies suggest that nematodes may serve as natural hosts for L. pneumophila, promote their persistence and dissemination in the environment, and co-evolutionarily pre-adapt the pathogen for interactions with extracellular constituents of human lung tissue. Copyright © 2016 Elsevier GmbH. All rights reserved.

Caenorhabditis elegans Predation on Bacillus anthracis: Decontamination of Spore Contaminated Soil with Germinants and Nematodes

PubMed Central

Schelkle, Bettina; Choi, Young; Baillie, Leslie W.; Richter, William; Buyuk, Fatih; Celik, Elif; Wendling, Morgan; Sahin, Mitat; Gallagher, Theresa

2018-01-01

Remediation of Bacillus anthracis-contaminated soil is challenging and approaches to reduce overall spore levels in environmentally contaminated soil or after intentional release of the infectious disease agent in a safe, low-cost manner are needed. B. anthracis spores are highly resistant to biocides, but once germinated they become susceptible to traditional biocides or potentially even natural predators such as nematodes in the soil environment. Here, we describe a two-step approach to reducing B. anthracis spore load in soil during laboratory trials, whereby germinants and Caenorhabditis elegans nematodes are applied concurrently. While the application of germinants reduced B. anthracis spore load by up to four logs depending on soil type, the addition of nematodes achieved a further log reduction in spore count. These laboratory based results suggest that the combined use of nematodes and germinants could represent a promising approach for the remediation of B. anthracis spore contaminated soil. Originality-Significance Statement: This study demonstrates for the first time the successful use of environmentally friendly decontamination methods to inactivate Bacillus anthracis spores in soil using natural predators of the bacterium, nematode worms. PMID:29379472

Olfactory circuits and behaviors of nematodes.

PubMed

Rengarajan, Sophie; Hallem, Elissa A

2016-12-01

Over one billion people worldwide are infected with parasitic nematodes. Many parasitic nematodes actively search for hosts to infect using volatile chemical cues, so understanding the olfactory signals that drive host seeking may elucidate new pathways for preventing infections. The free-living nematode Caenorhabditis elegans is a powerful model for parasitic nematodes: because sensory neuroanatomy is conserved across nematode species, an understanding of the microcircuits that mediate olfaction in C. elegans may inform studies of olfaction in parasitic nematodes. Here we review circuit mechanisms that allow C. elegans to respond to odorants, gases, and pheromones. We also highlight work on the olfactory behaviors of parasitic nematodes that lays the groundwork for future studies of their olfactory microcircuits. Copyright © 2016 Elsevier Ltd. All rights reserved.

The reindeer abomasal nematode (Ostertagia gruehneri) is naturally transmitted to sheep when sharing pastures.

PubMed

Manninen, Saana-Maaria; Thamsborg, Stig M; Laaksonen, Sauli; Oksanen, Antti

2014-11-01

The increasing number of sheep (Ovis aries) in northern Finland, often alternately corralled with winter-fed reindeer (Rangifer tarandus tarandus), creates potential for cross-infection of gastrointestinal nematodes. The aim of this study was to elucidate this possibility with 43 animals. Eleven reindeer and 8 sheep had shared a corral by turns, reindeer during winters, and sheep in summers. Another 12 reindeer had no known contact with sheep. Twelve sheep had no close contact to other ruminants. Both reindeer groups were free-ranging during summers. During slaughter in September to November, 2003, abomasa and parts of intestines were collected. Gastrointestinal nematodes were counted and identified. The species found were the following: in reindeer, Ostertagia gruehneri/Ostertagia arctica, Mazamastrongylus dagestanica, Nematodirus tarandi, Nematodirella longissimespiculata and Bunostomum trigonocephalum; in sheep, Teladorsagia circumcincta/Teladorsagia trifurcata, O. gruehneri/O. arctica, Nematodirus filicollis and N. spathiger. In the sheep sharing corral with reindeer, the only abomasal nematode species found was O. gruehneri, a reindeer parasite. The generation interval of O. gruehneri in Finnish reindeer appears to be shorter than in Canadian Arctic caribou, where complete larval inhibition leading to only one generation yearly has been reported.

Efficacy of the amino-acetonitrile derivative, monepantel, against experimental and natural adult stage gastro-intestinal nematode infections in sheep.

PubMed

Sager, Heinz; Hosking, Barry; Bapst, Béatrice; Stein, Philip; Vanhoff, Kathleen; Kaminsky, Ronald

2009-01-22

Multiple drug resistance by nematodes, against anthelmintics has become an important economic problem in sheep farming worldwide. Here we describe the efficacy of monepantel, a developmental molecule from the recently discovered anthelmintic class, the amino-acetonitrile derivatives (AADs). Efficacy was tested against adult stage gastro-intestinal nematodes (GINs) in experimentally and naturally infected sheep at a dose of 2.5mg/kg body weight when administered as an oral solution. Some of the isolates used in experimental infection studies were known to be resistant to the benzimidazoles or levamisole anthelmintics; strains resistant to the macrocyclic lactones were not available for these tests. Worm count-based efficacies of >98% were determined in these studies. As an exception, Oesophagostomum venulosum was only reduced by 88% in one study, albeit with a low worm burden in the untreated controls (geometric mean 15.4 worms). Similar efficacies for monepantel were also confirmed in naturally infected sheep. While the efficacy against most species was >99%, the least susceptible species was identified as Nematodirus spathiger, and although efficacy was 92.4% in one study it was generally >99%. Several animals were infected with Trichuris ovis, which was not eliminated after the treatment. Monepantel demonstrated high activity against a broad range of the important GINs of sheep, which makes this molecule an interesting candidate for use in this species, particularly in regions with problems of anthelmintic resistance. Monepantel was well tolerated by the treated sheep, with no treatment related adverse events documented.

Effects of Interactions of Auxin-Producing Bacteria and Bacterial-Feeding Nematodes on Regulation of Peanut Growths

PubMed Central

Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

2015-01-01

The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil. PMID:25867954

Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

PubMed

Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

2015-01-01

The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.

Discovery of genomic intervals that underlie nematode responses to benzimidazoles.

PubMed

Zamanian, Mostafa; Cook, Daniel E; Zdraljevic, Stefan; Brady, Shannon C; Lee, Daehan; Lee, Junho; Andersen, Erik C

2018-03-01

Parasitic nematodes impose a debilitating health and economic burden across much of the world. Nematode resistance to anthelmintic drugs threatens parasite control efforts in both human and veterinary medicine. Despite this threat, the genetic landscape of potential resistance mechanisms to these critical drugs remains largely unexplored. Here, we exploit natural variation in the model nematodes Caenorhabditis elegans and Caenorhabditis briggsae to discover quantitative trait loci (QTL) that control sensitivity to benzimidazoles widely used in human and animal medicine. High-throughput phenotyping of albendazole, fenbendazole, mebendazole, and thiabendazole responses in panels of recombinant lines led to the discovery of over 15 QTL in C. elegans and four QTL in C. briggsae associated with divergent responses to these anthelmintics. Many of these QTL are conserved across benzimidazole derivatives, but others show drug and dose specificity. We used near-isogenic lines to recapitulate and narrow the C. elegans albendazole QTL of largest effect and identified candidate variants correlated with the resistance phenotype. These QTL do not overlap with known benzimidazole target resistance genes from parasitic nematodes and present specific new leads for the discovery of novel mechanisms of nematode benzimidazole resistance. Analyses of orthologous genes reveal conservation of candidate benzimidazole resistance genes in medically important parasitic nematodes. These data provide a basis for extending these approaches to other anthelmintic drug classes and a pathway towards validating new markers for anthelmintic resistance that can be deployed to improve parasite disease control.

Experimental Evolution with Caenorhabditis Nematodes

PubMed Central

Teotónio, Henrique; Estes, Suzanne; Phillips, Patrick C.; Baer, Charles F.

2017-01-01

The hermaphroditic nematode Caenorhabditis elegans has been one of the primary model systems in biology since the 1970s, but only within the last two decades has this nematode also become a useful model for experimental evolution. Here, we outline the goals and major foci of experimental evolution with C. elegans and related species, such as C. briggsae and C. remanei, by discussing the principles of experimental design, and highlighting the strengths and limitations of Caenorhabditis as model systems. We then review three exemplars of Caenorhabditis experimental evolution studies, underlining representative evolution experiments that have addressed the: (1) maintenance of genetic variation; (2) role of natural selection during transitions from outcrossing to selfing, as well as the maintenance of mixed breeding modes during evolution; and (3) evolution of phenotypic plasticity and its role in adaptation to variable environments, including host–pathogen coevolution. We conclude by suggesting some future directions for which experimental evolution with Caenorhabditis would be particularly informative. PMID:28592504

Improving resilience against natural gastrointestinal nematode infections in browsing kids during the dry season in tropical Mexico.

PubMed

Torres-Acosta, J F J; Jacobs, D E; Aguilar-Caballero, A J; Sandoval-Castro, C; Cob-Galera, L; May-Martínez, M

2006-01-30

The objective was to determine the effect of supplementary feeding on the resilience and resistance of Criollo kids against natural gastrointestinal nematode (GIN) infections, when browsing native vegetation during the dry season in tropical Mexico. Thirty-three two-month-old Criollo kids, raised nematode free, were included at weaning in a 20-week trial. The kids were placed into four groups. Two groups of eight kids were offered 100g/day soybean and sorghum meal (26%:74% respectively fresh basis) (treated/supplemented (T-S) and infected/supplemented (I-S)). Two groups remained with no supplement for the duration of the trial (infected/non-supplemented (I-NS) (n=9) and treated/non-supplemented (T-NS) (n=8)). Kids in groups T-S and T-NS were drenched with 0.2mg of moxidectin/kg body weight orally (Cydectin, Fort Dodge) every 28 days. Groups I-S and I-NS were naturally infected with GIN. The animals browsed native vegetation for an average of 7h/day together with a herd of 120 naturally infected adult goats. Cumulative live weight gain (CLWG), packed cell volume (PCV), haemoglobin (Hb), total plasma protein and plasma albumin were recorded every 14 days as measurements of resilience. Resistance parameters (faecal egg counts (FEC) and peripheral eosinophil counts (PEC)) were also measured. Bulk faecal cultures were made for each group every 28 days. Every month a new pair of initially worm-free tracer kids assessed the infectivity of the vegetation browsed by the animals. Tracer kids and faecal cultures showed that kids faced low mixed infections (Haemonchus contortus, Trichostrongylus colubriformis and Oesophagostomum columbianum). Under conditions of scarce vegetation, such as those in the present study, supplemented groups (I-S and T-S) had higher growth rates compared to the non-supplemented groups independently of the control of GIN infection with anthelmintic (AH) treatment (P<0.001). Supplementary feeding did not affect FEC or PEC. In the absence of

Origins of Nematode Parasitism in the Families Strongyloididae, Rhabditidae, Plectidae and Diplogasteridae

NASA Astrophysics Data System (ADS)

Sachson, W.; Ngo, K.; Heim, N.; Payne, J.

2016-12-01

Parasitism is a fairly common trait found in the animal kingdom, and the effects parasites have on organisms is closely studied. On the other hand, how many different organisms evolve to become parasites is relatively unstudied, but trends between the size of these parasites and their environment may hold clues to their emergence. By looking at the size of parasitic nematodes, their free-living relatives and their environments, it is possible to deduce the cause of the parasitic tendencies of these families. In regard to nematodes, comparison of their body size and lifestyle does indeed reveal a trend between parasitic and free-living species. Many nematodes within the same family have evolved drastically different lifestyles within the same environment, and some have evolved when a new environment is available. In particular, the families Rhabditidae, Strongyloididae, Plectidae, and Diplogasteridae show abnormal ratios of parasite species to free-living species compared to others, in the case of Rhabditidae nearing a 1:1 ratio. Most importantly, the nature of each departure from each lifestyle appears to influence the size of the organism. What has been noticed in parasites can be described as an adaptation of Foster's Rule, which dictates the size of parasites depending on the environment and ecology of their ancestor. First of all, parasites change their size depending on their available resources. When free-living nematodes are given the opportunity to parasitize another organism, their body size changes in respect to the abundance of nutrients the nematode can extract from the host, which tends to let nematodes grow larger. On the other hand, when a parasitic nematode exits from parasitism to live freely or is parasitizing an organism within their natural environment, their size should decrease as they do not have access to as many resources as they did before. Using this idea, it is possible to understand the origins of parasitism and how organisms are driven

Molecular aspects of cyst nematodes.

PubMed

Lilley, Catherine J; Atkinson, Howard J; Urwin, Peter E

2005-11-01

SUMMARY Taxonomy: Superkingdom Eukaryota; kingdom Metazoa; phylum Nematoda; class Chromadorea; order Tylenchida; suborder Tylenchina; superfamily Tylenchoidea; family Heteroderidae; subfamily Heteroderinae; main genera Heterodera and Globodera. Cyst nematodes comprise approximately 100 known species in six genera. They are pathogens of temperate, subtropical and tropical plant species and the host range of many species is narrow. The most economically important species are within the Globodera and Heterodera genera. Globodera pallida and G. rostochiensis are important pathogens of potato crops. There are many economic species in the Heterodera genus, including Heterodera glycines (soybean cyst nematode), H. avenae (cereal cyst nematode) and H. schachtii (sugar beet cyst nematode), the last of which attacks a range of Chenopodiaceae and Cruciferae, including Arabidopsis thaliana. Disease symptoms: Field symptoms of severe cyst nematode infection are often stunting, wilting and chlorosis, but considerable yield loss can occur without obvious symptoms. The only unique indicator of cyst nematode infection is the presence of adult female nematodes attached to host roots after several weeks of parasitism. Disease control: This is usually achieved by using integrated pest management involving cultural practices such as crop rotation, resistant cultivars if available and chemical control when economically justified.

Origin, distribution and 3D-modeling of Gr-EXPB1, an expansin from the potato cyst nematode Globodera rostochiensis.

PubMed

Kudla, Urszula; Qin, Ling; Milac, Adina; Kielak, Anna; Maissen, Cyril; Overmars, Hein; Popeijus, Herman; Roze, Erwin; Petrescu, Andrei; Smant, Geert; Bakker, Jaap; Helder, Johannes

2005-04-25

Southern analysis showed that Gr-EXPB1, a functional expansin from the potato cyst nematode Globodera rostochiensis, is member of a multigene family, and EST data suggest expansins to be present in other plant parasitic nematodes as well. Homology modeling predicted that Gr-EXPB1 domain 1 (D1) has a flat beta-barrel structure with surface-exposed aromatic rings, whereas the 3D structure of Gr-EXPB1-D2 was remarkably similar to plant expansins. Gr-EXPB1 shows highest sequence similarity to two extracellular proteins from saprophytic soil-inhabiting Actinobacteria, and includes a bacterial type II carbohydrate-binding module. These results support the hypothesis that a number of pathogenicity factors of cyst nematodes is of procaryotic origin and were acquired by horizontal gene transfer.

A comparative analysis of benthic nematode assemblages from Zostera noltii beds before and after a major vegetation collapse

NASA Astrophysics Data System (ADS)

Materatski, Patrick; Vafeiadou, Anna-Maria; Ribeiro, Rui; Moens, Tom; Adão, Helena

2015-12-01

Benthic nematodes are widely regarded as very suitable organisms to monitor potential ecological effects of natural and anthropogenic disturbances in aquatic ecosystems. During 2008, the seagrass beds of Zostera noltii located in the Mira estuary (SW Portugal) disappeared completely. However, during 2009, slight symptoms of natural recovery were observed, a process which has since evolved intermittently. This study aims to investigate changes in patterns of nematode density, diversity, and trophic composition between two distinct habitat conditions: "before" the collapse of seagrass beds, and during the early recovery "after" the seagrass habitat loss, through the analysis of: i) temporal and spatial distribution patterns of nematode communities, and ii) the most important environmental variables influencing the nematode assemblages. The following hypotheses were tested: i) there would be differences in nematode assemblage density, biodiversity and trophic composition during both ecological conditions, "before" and "after"; and ii) there would be differences in nematode assemblage density, biodiversity and trophic composition at different sampling occasions during both ecological conditions. Nematode density and diversity were significantly different between the two ecological situations. A higher density was recorded before, but a higher diversity was evident after the collapse of Z. noltii. In spite of the disturbance caused by the seagrass habitat loss in the Mira estuary, the nematode trophic composition did not significantly differ between the before and after seagrass collapse situations. Despite the significant differences found among sampling occasions, a consistent temporal pattern was not evident. The response of nematode communities following this extreme event exhibited considerable resistance and resilience to the new environmental conditions.

Damage-associated responses of the host contribute to defence against cyst nematodes but not root-knot nematodes.

PubMed

Shah, Syed Jehangir; Anjam, Muhammad Shahzad; Mendy, Badou; Anwer, Muhammad Arslan; Habash, Samer S; Lozano-Torres, Jose L; Grundler, Florian M W; Siddique, Shahid

2017-12-16

When nematodes invade and subsequently migrate within plant roots, they generate cell wall fragments (in the form of oligogalacturonides; OGs) that can act as damage-associated molecular patterns and activate host defence responses. However, the molecular mechanisms mediating damage responses in plant-nematode interactions remain unexplored. Here, we characterized the role of a group of cell wall receptor proteins in Arabidopsis, designated as polygalacturonase-inhibiting proteins (PGIPs), during infection with the cyst nematode Heterodera schachtii and the root-knot nematode Meloidogyne incognita. PGIPs are encoded by a family of two genes in Arabidopsis, and are involved in the formation of active OG elicitors. Our results show that PGIP gene expression is strongly induced in response to cyst nematode invasion of roots. Analyses of loss-of-function mutants and overexpression lines revealed that PGIP1 expression attenuates infection of host roots by cyst nematodes, but not root-knot nematodes. The PGIP1-mediated attenuation of cyst nematode infection involves the activation of plant camalexin and indole-glucosinolate pathways. These combined results provide new insights into the molecular mechanisms underlying plant damage perception and response pathways during infection by cyst and root-knot nematodes, and establishes the function of PGIP in plant resistance to cyst nematodes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of Ascaris reveals a novel fold and two discrete lipid-binding sites.

PubMed

Meenan, Nicola A G; Ball, Graeme; Bromek, Krystyna; Uhrín, Dušan; Cooper, Alan; Kennedy, Malcolm W; Smith, Brian O

2011-04-19

Nematode polyprotein allergens (NPAs) are an unusual class of lipid-binding proteins found only in nematodes. They are synthesized as large, tandemly repetitive polyproteins that are post-translationally cleaved into multiple copies of small lipid binding proteins with virtually identical fatty acid and retinol (Vitamin A)-binding characteristics. They are probably central to transport and distribution of small hydrophobic compounds between the tissues of nematodes, and may play key roles in nutrient scavenging, immunomodulation, and IgE antibody-based responses in infection. In some species the repeating units are diverse in amino acid sequence, but, in ascarid and filarial nematodes, many of the units are identical or near-identical. ABA-1A is the most common repeating unit of the NPA of Ascaris suum, and is closely similar to that of Ascaris lumbricoides, the large intestinal roundworm of humans. Immune responses to NPAs have been associated with naturally-acquired resistance to infection in humans, and the immune repertoire to them is under strict genetic control. The solution structure of ABA-1A was determined by protein nuclear magnetic resonance spectroscopy. The protein adopts a novel seven-helical fold comprising a long central helix that participates in two hollow four-helical bundles on either side. Discrete hydrophobic ligand-binding pockets are found in the N-terminal and C-terminal bundles, and the amino acid sidechains affected by ligand (fatty acid) binding were identified. Recombinant ABA-1A contains tightly-bound ligand(s) of bacterial culture origin in one of its binding sites. This is the first mature, post-translationally processed, unit of a naturally-occurring tandemly-repetitive polyprotein to be structurally characterized from any source, and it belongs to a new structural class. NPAs have no counterparts in vertebrates, so represent potential targets for drug or immunological intervention. The nature of the (as yet) unidentified bacterial

Yellow Pigment Aurovertins Mediate Interactions between the Pathogenic Fungus Pochonia chlamydosporia and Its Nematode Host.

PubMed

Wang, Yan-li; Li, Lin-fang; Li, Dong-xian; Wang, Baile; Zhang, Keqin; Niu, Xuemei

2015-07-29

Nematophagous fungi are globally distributed soil fungi and well-known natural predators of soil-dwelling nematodes. Pochonia chlamydosporia can be found in diverse nematode-suppressive soils as a parasite of nematode eggs and is one of the most studied potential biological control agents of nematodes. However, little is known about the functions of small molecules in the process of infection of nematodes by this parasitic fungus or about small-molecule-mediated interactions between the pathogenic fungus and its host. Our recent study demonstrated that a P. chlamydosporia strain isolated from root knots of tobacco infected by the root-knot nematode Meloidogyne incognita produced a class of yellow pigment metabolite aurovertins, which induced the death of the free-living nematode Panagrellus redivevus. Here we report that nematicidal P. chlamydosporia strains obtained from the nematode worms tended to yield a total yellow pigment aurovertin production exceeding the inhibitory concentration shown in nematicidal bioassays. Aurovertin D was abundant in the pigment metabolites of P. chlamydosporia strains. Aurovertin D showed strong toxicity toward the root-knot nematode M. incognita and exerted profound and detrimental effects on the viability of Caenorhabditis elegans even at a subinhibitory concentration. Evaluation of the nematode mutation in the β subunit of F1-ATPase, together with the application of RNA interference in screening each subunit of F1FO-ATPase in the nematode worms, demonstrated that the β subunit of F1-ATPase might not be the specific target for aurovertins in nematodes. The resistance of C. elegans daf-2(e1370) and the hypersensitivity of C. elegans daf-16(mu86) to aurovertin D indicated that DAF-16/FOXO transcription factor in nematodes was triggered in response to the aurovertin attack. These findings advance our understanding of the roles of aurovertin production in the interactions between nematodes and the pathogen fungus P. chlamydosporia.

Coprinus comatus damages nematode cuticles mechanically with spiny balls and produces potent toxins to immobilize nematodes.

PubMed

Luo, Hong; Liu, Yajun; Fang, Lin; Li, Xuan; Tang, Ninghua; Zhang, Keqin

2007-06-01

We reported recently a unique fungal structure, called the spiny ball, on the vegetative hyphae of Coprinus comatus (O. F. Müll.:Fr.) Pers. Although some observations regarding the role of this structure were presented, its function remained largely unknown. In this study, we showed that purified (isolated and washed) spiny balls could immobilize and kill the free-living nematode Panagrellus redivivus Goodey highly efficiently. Scanning electron microscopy studies illustrated that the spiny structure damaged the nematode cuticle, suggesting the presence of a mechanical force during the process of nematode immobilization. Severe injuries on nematode cuticles caused the leakage of inner materials of the nematodes. When these structures were ground in liquid nitrogen, their killing efficacy against nematodes was lost, indicating that the shape and the complete structure of the spiny balls are indispensable for their function. However, extraction with organic solvents never lowered their activity against P. redivivus, and the extracts showed no obvious effect on the nematode. We also investigated whether C. comatus was able to produce toxins which would aid in the immobilization of nematodes. In total, we identified seven toxins from C. comatus that showed activity to immobilize the nematodes P. redivivus and Meloidogyne incognita (Kofoid et White) Chitwood. The chemical structures of these toxins were identified with nuclear magnetic resonance, mass spectrometry, infrared, and UV spectrum analysis. Two compounds were found to be novel. The toxins found in C. comatus are O-containing heterocyclic compounds.

'Candidatus pasteuria usgae' sp. nov., an obligate endoparasite of the phytoparasitic nematode Belonolaimus longicaudatus.

PubMed

Giblin-Davis, R M; Williams, D S; Bekal, S; Dickson, D W; Brito, J A; Becker, J O; Preston, J F

2003-01-01

Taxonomically relevant characteristics of a fastidiously Gram-positive, obligately endoparasitic prokaryote (strain S-1) that uses the phytoparasitic sting nematode Belonolaimus longicaudatus as its host are reviewed. 16S rDNA sequence similarity (> or = 93%) confirms its congeneric ranking with other Pasteuria species and strains from nematodes and cladocerans and corroborates morphological, morphometric and host range evidence suggesting a novel taxon. The 16S rDNA sequence of strain S-1 has greatest similarity (96%) to the 16S rDNA sequences of both Pasteuria penetrans from root-knot nematodes (Meloidogyne species) and the recently reported strain of Pasteuria isolated from the soybean cyst nematode Heterodera glycines. Because the obligately endoparasitic nature of prokaryotes in the genus Pasteuria prevents isolation of definitive type strains, strain S-1 is proposed as 'Candidatus Pasteuria usgae' sp. nov.

Nematode larvae infecting Priacanthus arenatus Cuvier, 1829 (Pisces: Teleostei) in Brazil.

PubMed

Kuraiem, Bianca P; Knoff, Marcelo; Felizardo, Nilza N; Gomes, Delir C; Clemente, Sérgio C São

2016-05-31

From July to December, 2013, thirty Priacanthus arenatus specimens commercialized in the cities of Niterói and Rio de Janeiro, State of Rio de Janeiro, were acquired. The fish were necropsied and filleted to investigate the presence of nematode larvae. Twenty fish (66.7%) out of the total were parasitized by nematode larvae. A total of 2024 larvae were collected; among them, 30 third-instar larvae of Anisakis sp. showed prevalence (P) = 20%, mean abundance (MA) = 1, and the mean intensity (MI) = 5, and infection sites (IS) = caecum, stomach, liver, and mesentery; and 1,994 third-instar larvae (1,757 encysted and 237 free) of Hysterothylacium deardorffoverstreetorum with P = 66.7%, MA = 66.5, and MI = 99.7, and IS = spleen, caecum, stomach, liver, mesentery, and abdominal muscle. This is the first study to report H. deardorffoverstreetorum and Anisakis sp. larvae parasitizing P. arenatus.

Nematode grazing promotes bacterial community dynamics in soil at the aggregate level

PubMed Central

Jiang, Yuji; Liu, Manqiang; Zhang, Jiabao; Chen, Yan; Chen, Xiaoyun; Chen, Lijun; Li, Huixin; Zhang, Xue-Xian; Sun, Bo

2017-01-01

Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial–microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner. PMID:28742069

Nematode grazing promotes bacterial community dynamics in soil at the aggregate level.

PubMed

Jiang, Yuji; Liu, Manqiang; Zhang, Jiabao; Chen, Yan; Chen, Xiaoyun; Chen, Lijun; Li, Huixin; Zhang, Xue-Xian; Sun, Bo

2017-12-01

Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial-microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner.

Differential Selection by Nematodes on an Introduced Biocontrol Fungus vs. Indigenous Fungi in Nonsterile Soil.

PubMed

Kim, Tae Gwan; Knudsen, Guy R

2018-03-15

Trophic interactions of introduced biocontrol fungi with soil animals can bea key determinant in the fungal proliferation and activity.This study investigated trophic interaction of an introduced biocontrol fungus with soil nematodes. The biocontrol fungus Trichoderma harzianum ThzID1-M3 and the fungivorous nematode Aphelenchoides sp. (10 per gram of soil) were added to nonsterile soil, and microbial populations were monitored for 40 days. Similar results were obtained when the experiment was duplicated. ThzID1-M3 stimulated the population growth of indigenous nematodes ( p <0.05), regardless of whether Aphelenchoides sp.was added.Without ThzID1-M3, indigenous nematodes did not increase in number and the added Aphelenchoides sp. nematodes almost disappeared by day 10. With ThzID1-M3, population growth of nematodes was rapid between 5 and 10 days after treatment. ThzID1-M3 biomass peaked on day 5, dropped at day 10, and then almost disappeared at day 20, which was not influenced by the addition of nematodes.In contrast, a large quantity of ThzID1-M3 hyphae were present in a heat-treated soil in which nematodes were eliminated.Total fungal biomass in all treatments peaked on day 5 and subsequently decreased.Addition of nematodes increased the total fungal biomass ( p <0.05), but ThzID1-M3 addition did not affect the fungal biomass.Hyphae oftotal fungi when homogenously distributed did not support the nematode population growth; however, hyphae of the introduced fungus when densely localized did.The results suggest that soil fungivorous nematodes are an important constraint onhyphal proliferation of fungal agents introduced into natural soils.

Nematode cholinergic pharmacology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Segerberg, M.A.

1989-01-01

Nematode acetylcholine (ACh) receptors were characterized using both biochemical and electrophysiological techniques, including: (1) receptor binding studies in crude homogenates of the free-living nematode Caenorhabditis elegans and the parasitic nematode Ascaris lumbricoides with the high-affinity probe ({sup 3}H)N-methylscopolamine (({sup 3}H)NMS) which binds to muscarinic receptors in many vertebrate and invertebrate tissues (2) measurement of depolarization and contraction induced by a variety of cholinergic agents, including N-methylscopolamine (NMS), in an innervated dorsal muscle strip preparation of Ascaris; (3) examination of the antagonistic actions of d-tubocurarine (dTC) and NMS at dorsal neuromuscular junction; (4) measurement of input resistance changes in Ascaris commissuralmore » motorneurons induced by ACh, dTC, NMS, pilocarpine and other cholinergic drugs.« less

Small RNAs and extracellular vesicles in filarial nematodes: From nematode development to diagnostics.

PubMed

Quintana, J F; Babayan, S A; Buck, A H

2017-02-01

Parasitic nematodes have evolved sophisticated mechanisms to communicate with their hosts in order to survive and successfully establish an infection. The transfer of RNA within extracellular vesicles (EVs) has recently been described as a mechanism that could contribute to this communication in filarial nematodes. It has been shown that these EVs are loaded with several types of RNAs, including microRNAs, leading to the hypothesis that parasites could actively use these molecules to manipulate host gene expression and to the exciting prospect that these pathways could result in new diagnostic and therapeutic strategies. Here, we review the literature on the diverse RNAi pathways that operate in nematodes and more specifically our current knowledge of extracellular RNA (exRNA) and EVs derived from filarial nematodes in vitro and within their hosts. We further detail some of the issues and questions related to the capacity of RNA-mediated communication to function in parasite-host interactions and the ability of exRNA to enable us to distinguish and detect different nematode parasites in their hosts. © 2016 The Authors. Parasite Immunology published by John Wiley & Sons Ltd.

Plant-parasitic nematodes in Hawaiian agriculture

USDA-ARS?s Scientific Manuscript database

Hawaii’s diverse and mild climate allows for the cultivation of many crops. The introduction of each crop plant brought along its associated nematode pests. These plant-parasitic nematodes became established and are now endemic to the islands. Plantation agriculture determined the major nematode ...

Unraveling the intraguild competition between Oscheius spp. nematodes and entomopathogenic nematodes: Implications for their natural distribution in Swiss agricultural soils.

PubMed

Campos-Herrera, Raquel; Půža, Vladimir; Jaffuel, Geoffrey; Blanco-Pérez, Rubén; Čepulytė-Rakauskienė, Rasa; Turlings, Ted C J

2015-11-01

Entomopathogenic nematodes (EPN) are excellent biological control agents to fight soil-dwelling insect pests. In a previous survey of agricultural soils of Switzerland, we found mixtures of free-living nematodes (FLN) in the genus Oscheius, which appeared to be in intense competition with EPN. As this may have important implications for the long-term persistence of EPN, we studied this intraguild competition in detail. We hypothesized that (i) Oscheius spp. isolates act as scavengers rather than entomopathogens, and (ii) cadavers with relatively small numbers of EPN are highly suitable resources for Oscheius spp. reproduction. To study this, we identified Oscheius spp. isolated from Swiss soils, quantified the outcome of EPN/Oscheius competition in laboratory experiments, developed species-specific primers and probe for quantitative real-time PCR, and evaluated their relative occurrence in the field in the context of the soil food web. Molecular analysis (ITS/D2D3) identified MG-67/MG-69 as Oscheius onirici and MG-68 as O. tipulae (Dolichura-group). Oscheius spp. indeed behaved as scavengers, reproducing in ∼64% of frozen-killed cadavers from controlled experiments. Mixed infection in the laboratory by Oscheius spp. with low (3 IJs) or high (20 IJs) initial EPN numbers revealed simultaneous reproduction in double-exposed cadavers which resulted in a substantial reduction in the number of EPN progeny from the cadaver. This effect depended on the number of EPN in the initial inoculum and differed by EPN species; Heterorhabditis megidis was better at overcoming competition. This study reveals Oscheius spp. as facultative kleptoparasites that compete with EPN for insect cadavers. Using real-time qPCR, we were able to accurately quantify this strong competition between FLN and EPN in cadavers that were recovered after soil baiting (∼86% cadavers with >50% FLN production). The severe competition within the host cadavers and the intense management of the soils in

Nematodes inhabit soils of forest and clear-cut areas

Treesearch

Alex L. Shigo; George Yelenosky

1960-01-01

Nematodes are present in all forest soils, but their effects on forest trees are not known. The known destructive nature of these worms on other woody crops suggests that they may also be involved in causing some of the unexplainable losses in vigor and mortality of forest trees.

Marine Nematode Taxonomy in Africa: Promising Prospects Against Scarcity of Information

PubMed Central

Boufahja, Fehmi; Semprucci, Federica; Beyrem, Hamouda; Bhadury, Punyasloke

2015-01-01

From the late 19th century, Africa has faced heavy exploitation of its natural resources with increasing land/water pollution, and several described species have already become extinct or close to extinction. This could also be the case for marine nematodes, which are the most abundant and diverse benthic group in marine sediments, and play major roles in ecosystem functioning. Compared to Europe and North America, only a handful of investigations on marine nematodes have been conducted to date in Africa. This is due to the scarcity of experienced taxonomists, absence of identification guides, as well as local appropriate infrastructures. A pivotal project has started recently between nematologists from Africa (Tunisia), India, and Europe (Italy) to promote taxonomic study and biodiversity estimation of marine nematodes in the African continent. To do this, as a first step, collection of permanent slides of marine nematodes (235 nominal species and 14 new to science but not yet described) was recently established at the Faculty of Sciences of Bizerte (Tunisia). Capacity building of next generation of African taxonomists have been carried out at level of both traditional and molecular taxonomy (DNA barcoding and next-generation sequencing [NGS]), but they need to be implemented. Indeed, the integration of these two approaches appears crucial to overcome lack of information on the taxonomy, ecology, and biodiversity of marine nematodes from African coastal waters. PMID:26527841

Sex-specific lifespan and its evolution in nematodes.

PubMed

Ancell, Henry; Pires-daSilva, Andre

2017-10-01

Differences between sexes of the same species in lifespan and aging rate are widespread. While the proximal and evolutionary causes of aging are well researched, the factors that contribute to sex differences in these traits have been less studied. The striking diversity of nematodes provides ample opportunity to study variation in sex-specific lifespan patterns associated with shifts in life history and mating strategy. Although the plasticity of these sex differences will make it challenging to generalize from invertebrate to vertebrate systems, studies in nematodes have enabled empirical evaluation of predictions regarding the evolution of lifespan. These studies have highlighted how natural and sexual selection can generate divergent patterns of lifespan if the sexes are subject to different rates or sources of mortality, or if trade-offs between complex traits and longevity are resolved differently in each sex. Here, we integrate evidence derived mainly from nematodes that addresses the molecular and evolutionary basis of sex-specific aging and lifespan. Ultimately, we hope to generate a clearer picture of current knowledge in this area, and also highlight the limitations of our understanding. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Anthelmintic efficacy of Nauclea latifolia extract against gastrointestinal nematodes of sheep: in vitro and in vivo studies.

PubMed

Ademola, I O; Fagbemi, B O; Idowu, S O

2006-11-13

Direct effects of Nauclea latifolia extracts on different gastrointestinal nematodes of sheep is described. In vivo and in vitro studies were conducted to determine possible anthelmintic effect of leaf extracts of Nauclea latifolia toward different ovine gastro intestinal nematodes. A larval development assay was used to investigate in vitro, the effect of aqueous and ethanolic extracts of N. latifolia towards strongyles larvae. The development and survival of infective larvae (L(3)) was assessed and best-fit LC(50) values were computed by global model of non-linear regression analysis curve-fitting (95% CI). Twenty sheep harbouring naturally acquired gastrointestinal nematodes were treated with oral administration of ethanolic extracts at a dose rate of 125 mg/kg, 250 mg/kg and 500 mg/kg to evaluate therapeutic efficacy, in vivo.The presence of the extracts in the cultures decreased the survival of larvae. The LC(50) of aqueous and ethanolic extract were 0.704 and 0.650 mg/ml respectively and differ significantly (P<0.05, paired t test). Faecal egg counts (FEC) on day 12 after treatment showed that the extract is effective, relative to control (1-way ANOVA, Dunnett's multiple comparison test), at 500 mg/kg against Haemonchus spp, Trichostrongylus spp (p<0.05), Strongyloides spp (P < 0.01); at 250 mg/kg against Trichuris spp (P < 0.01) and ineffective against Oesophagostomum spp (p>0.05). The effect of doses is extremely significant; the day after treatment is sometimes significant while interaction between dose and day after treatment is insignificant (2-way ANOVA). N. latifolia extract could therefore find application in the control of helminth in livestock, by the ethnoveterinary medicine approach.

The Nematode Caenorhabditis Elegans.

ERIC Educational Resources Information Center

Kenyon, Cynthia

1988-01-01

Discusses advantages of nematode use for studying patterns of cell division, differentiation, and morphogenesis. Describes nematode development. Cites experimental approaches available for genetic studies. Reviews the topics of control of cell division and differentiation, the nervous system, and muscle assembly and function of the organism. (RT)

Nematodes ultrastructure: complex systems and processes.

PubMed

Basyoni, Maha M A; Rizk, Enas M A

2016-12-01

Nematode worms are among the most ubiquitous organisms on earth. They include free-living forms as well as parasites of plants, insects, humans and other animals. Recently, there has been an explosion of interest in nematode biology, including the area of nematode ultrastructure. Nematodes are round with a body cavity. They have one way guts with a mouth at one end and an anus at the other. They have a pseudocoelom that is lined on one side with mesoderm and on the other side with endoderm. It appears that the cuticle is a very complex and evolutionarily plastic feature with important functions involving protection, body movement and maintaining shape. They only have longitudinal muscles so; they seem to thrash back and forth. While nematodes have digestive, reproductive, nervous and excretory systems, they do not have discrete circulatory or respiratory systems. Nematodes use chemosensory and mechanosensory neurons embedded in the cuticle to orient and respond to a wide range of environmental stimuli. Adults are made up of roughly 1000 somatic cells and hundreds of those cells are typically associated with the reproductive systems. Nematodes ultrastructure seeks to provide studies which enable their use as models for diverse biological processes including; human diseases, immunity, host-parasitic interactions and the expression of phylogenomics. The latter has, however, not been brought into a single inclusive entity. Consequently, in the current review we tried to provide a comprehensive approach to the current knowledge available for nematodes ultrastructures.

RNA-Seq reveals the molecular mechanism of trapping and killing of root-knot nematodes by nematode-trapping fungi.

PubMed

Pandit, Ramesh; Patel, Reena; Patel, Namrata; Bhatt, Vaibhav; Joshi, Chaitanya; Singh, Pawan Kumar; Kunjadia, Anju

2017-04-01

Nematode-trapping fungi are well known for their inherent potential to trap and kill nematodes using specialized trapping devices. However, the molecular mechanisms underlying the trapping and subsequent processes are still unclear. Therefore, in this study, we examined differential genes expression in two nematode-trapping fungi after baiting with nematode extracts. In Arthrobotrys conoides, 809 transcripts associated with diverse functions such as signal transduction, morphogenesis, stress response and peroxisomal proteins, proteases, chitinases and genes involved in the host-pathogen interaction showed differential expression with fold change (>±1.5 fold) in the presence of nematode extract with FDR (p-value < 0.001). G-proteins and mitogen activated protein kinases are considered crucial for signal transduction mechanism. Results of qRT-PCR of 20 genes further validated the sequencing data. Further, variations in gene expression among Duddingtonia flagrans and A. conoides showed septicity of nematode-trapping fungi for its host. The findings illustrate the molecular mechanism of fungal parasitism in A. conoides which may be helpful in developing a potential biocontrol agent against parasitic nematodes.

Evaluation of Clonostachys rosea for Control of Plant-Parasitic Nematodes in Soil and in Roots of Carrot and Wheat.

PubMed

Iqbal, Mudassir; Dubey, Mukesh; McEwan, Kerstin; Menzel, Uwe; Franko, Mikael Andersson; Viketoft, Maria; Jensen, Dan Funck; Karlsson, Magnus

2018-01-01

Biological control is a promising approach to reduce plant diseases caused by nematodes. We tested the effect of the fungus Clonostachys rosea strain IK726 inoculation on nematode community composition in a naturally nematode infested soil in a pot experiment, and the effect of C. rosea on plant health. The numbers of plant-parasitic nematode genera extracted from soil and plant roots decreased by 40 to 73% when C. rosea was applied, while genera of nonparasitic nematodes were not affected. Soil inoculation of C. rosea increased fresh shoot weight and shoot length of wheat plants by 20 and 24%, respectively, while only shoot dry weight increased by 48% in carrots. Light microscopy of in vitro C. rosea-nematode interactions did not reveal evidence of direct parasitism. However, culture filtrates of C. rosea growing in potato dextrose broth, malt extract broth and synthetic nutrient broth exhibited toxicity toward nematodes and immobilized 57, 62, and 100% of the nematodes, respectively, within 48 h. This study demonstrates that C. rosea can control plant-parasitic nematodes and thereby improve plant growth. The most likely mechanism responsible for the antagonism is antibiosis through production of nematicidal compounds, rather than direct parasitism.

Speech perception and reading: two parallel modes of understanding language and implications for acquiring literacy naturally.

PubMed

Massaro, Dominic W

2012-01-01

I review 2 seminal research reports published in this journal during its second decade more than a century ago. Given psychology's subdisciplines, they would not normally be reviewed together because one involves reading and the other speech perception. The small amount of interaction between these domains might have limited research and theoretical progress. In fact, the 2 early research reports revealed common processes involved in these 2 forms of language processing. Their illustration of the role of Wundt's apperceptive process in reading and speech perception anticipated descriptions of contemporary theories of pattern recognition, such as the fuzzy logical model of perception. Based on the commonalities between reading and listening, one can question why they have been viewed so differently. It is commonly believed that learning to read requires formal instruction and schooling, whereas spoken language is acquired from birth onward through natural interactions with people who talk. Most researchers and educators believe that spoken language is acquired naturally from birth onward and even prenatally. Learning to read, on the other hand, is not possible until the child has acquired spoken language, reaches school age, and receives formal instruction. If an appropriate form of written text is made available early in a child's life, however, the current hypothesis is that reading will also be learned inductively and emerge naturally, with no significant negative consequences. If this proposal is true, it should soon be possible to create an interactive system, Technology Assisted Reading Acquisition, to allow children to acquire literacy naturally.

Conflict of interest between a nematode and a trematode in an amphipod host: Test of the "sabotage" hypothesis

USGS Publications Warehouse

Thomas, Frédéric; Fauchier, Jerome; Lafferty, Kevin D.

2002-01-01

Microphallus papillorobustus is a manipulative trematode that induces strong behavioural alterations in the gamaridean amphipod Gammarus insensibilis, making the amphipod more vulnerable to predation by aquatic birds (definitive hosts). Conversely, the sympatric nematodeGammarinema gammari uses Gammarus insensibilis as a habitat and a source of nutrition. We investigated the conflict of interest between these two parasite species by studying the consequences of mixed infection on amphipod behaviour associated with the trematode. In the field, some amphipods infected by the trematode did not display the altered behaviour. These normal amphipods also had more nematodes, suggesting that the nematode overpowered the manipulation of the trematode, a strategy that would prolong the nematode's life. We hypothesize that sabotage of the trematode by the nematode would be an adaptive strategy for the nematode consistent with recent speculation about co-operation and conflict in manipulative parasites. A behavioural test conducted in the laboratory from naturally infected amphipods yielded the same result. However, exposing amphipods to nematodes did not negate or decrease the manipulation exerted by the trematode. Similarly, experimental elimination of nematodes from amphipods did not permit trematodes to manipulate behaviour. These experimental data do not support the hypothesis that the negative association between nematodes and manipulation by the trematode is a result of the "sabotage" hypothesis.

Efficacy of a topical combination of fipronil, (S)-methoprene, eprinomectin and praziquantel (Broadline(®)) against naturally acquired infections with cestodes of the genus Joyeuxiella in cats.

PubMed

Schuster, Rolf K; Mustafa, Murad Basheer; Baskar, Jagadeesan Vijay; Rosentel, Joseph; Chester, S Theodore; Knaus, Martin

2016-07-01

Cats are host to dipylidiid cestodes of the genera Diplopylidium, Dipylidium and Joyeuxiella. Broadline(®), a topical broad-spectrum combination parasiticide containing fipronil (8.3 % w/v), (S)-methoprene (10 % w/v), eprinomectin (0.4 % w/v) and the cestocide praziquantel (8.3 % w/v), has previously been shown to be efficacious against Dipylidium caninum and Diplopylidium spp. in cats. To evaluate its efficacy against Joyeuxiella species, a blinded clinical efficacy study was conducted according to GCP. All cats had evidence for naturally acquired dipylidiid cestode infection as confirmed by pre-treatment examination. Cats were allocated randomly to two groups of 13 cats each based on bodyweight: Control (untreated) and Broadline(®) at 0.12 mL/kg bodyweight administered once topically. Based on the comparison of helminth counts in the treated and untreated cats seven days post treatment, Broadline(®) demonstrated >99 % efficacy (p < 0.01) against mature J. fuhrmanni and J. pasqualei, with 11 and 13 of the untreated cats harbouring 1 to 102 or 2 to 95 cestodes, respectively. In addition, parasite counts indicated 95.9 % efficacy (p = 0.006) against the rictularoid nematode Pterygodermatites cahirensis.

Detection and quantification of root-knot nematode (Meloidogyne javanica), lesion nematode (Pratylenchus zeae) and dagger nematode (Xiphinema elongatum) parasites of sugarcane using real-time PCR.

PubMed

Berry, Shaun D; Fargette, Mireille; Spaull, Vaughan W; Morand, Serge; Cadet, Patrice

2008-06-01

A number of different plant parasitic nematode species are found associated with sugarcane in South Africa. Of these, the root-knot nematode (Meloidogyne javanica), the lesion nematode (Pratylenchus zeae) and the dagger nematode (Xiphinema elongatum) are potentially the most damaging pests. Identification and enumeration of the number of these nematodes are necessary for providing advice to farmers as well as studying the effects of various treatments in field and glasshouse trials. We report on the development, use, and extent of specificity of three sets of primers, for M. javanica, P. zeae and X. elongatum, and on tests to detect and quantify the number of these nematodes in soil samples using SYBR Green I dye and real-time PCR technology. Amplicons from the three target species (obtained with their respective primer sets) are discernible in size by gel electrophoresis (380bp for M. javanica, 250bp for P. zeae and 500bp for X. elongatum). Also, these amplicons have characteristic melting temperatures of 83.8 degrees C (M. javanica), 86.6 degrees C (P. zeae) and 86.1 degrees C (X. elongatum). Investigations into multiplex reactions found competition between species with M. javanica competing with P. zeae and X. elongatum. Subsequent single tube (simplex) assays, enabled the construction of calibration curves for each of the three species. These were then used for quantification of the numbers of each of these species in nematode samples extracted from the field, with a high (R2=0.83) and significant positive correlation between real-time PCR and counts performed with microscopy.

An improved method for generating axenic entomopathogenic nematodes.

PubMed

Yadav, Shruti; Shokal, Upasana; Forst, Steven; Eleftherianos, Ioannis

2015-09-19

Steinernema carpocapsae are parasitic nematodes that invade and kill insects. The nematodes are mutualistically associated with the bacteria Xenorhabdus nematophila and together form an excellent model to study pathogen infection processes and host anti-nematode/antibacterial immune responses. To determine the contribution of S. carpocapsae and their associated X. nematophila to the successful infection of insects as well as to investigate the interaction of each mutualistic partner with the insect immune system, it is important to develop and establish robust methods for generating nematodes devoid of their bacteria. To produce S. carpocapsae nematodes without their associated X. nematophila bacteria, we have modified a previous method, which involves the use of a X. nematophila rpoS mutant strain that fails to colonize the intestine of the worms. We confirmed the absence of bacteria in the nematodes using a molecular diagnostic and two rounds of an axenicity assay involving appropriate antibiotics and nematode surface sterilization. We used axenic and symbiotic S. carpocapsae to infect Drosophila melanogaster larvae and found that both types of nematodes were able to cause insect death at similar rates. Generation of entomopathogenic nematodes lacking their mutualistic bacteria provides an excellent tool to dissect the molecular and genetic basis of nematode parasitism and to identify the insect host immune factors that participate in the immune response against nematode infections.

Anthelmintic activity of Spigelia anthelmia extract against gastrointestinal nematodes of sheep.

PubMed

Ademola, I O; Fagbemi, B O; Idowu, S O

2007-06-01

In vitro (larval development assay) and in vivo studies were conducted to determine possible direct anthelmintic effect of ethanolic and aqueous extracts of Spigelia anthelmia towards different ovine gastrointestinal nematodes. The effect of extracts on development and survival of infective larvae stage (L(3)) was assessed. Best-fit LC(50) values were computed by global model of non-linear regression curve fitting (95% confidence interval). Therapeutic efficacy of the ethanolic extracts administered orally at a dose rate of 125, 250, and 500 mg/kg, relative to a non-medicated control group of sheep harbouring naturally acquired infection of gastrointestinal nematodes, was evaluated in vivo.The presence of S. anthelmia extracts in the cultures decreased the survival of L(3) larvae. The LC(50) of aqueous extract (0.714 mg/ml) differ significantly from the LC(50) of the ethanolic extract (0.628 mg/ml) against the strongyles (p < 0.05, paired t-test). Faecal egg counts on day 12 after treatment showed that the extract is effective, relative to control (one-way analysis of variance [ANOVA], Dunnett's multiple comparison test) at 500 mg/kg against Strongyloides spp. (p < 0.01), 250 mg/kg against Oesophagostomum spp., Trichuris spp. (p < 0.05), and 125 mg/kg against Haemonchus spp. and Trichostrongylus spp. (p < 0.01). The effect of the doses is significant in all cases, the day after treatment is also extremely significant in most cases, whereas interaction between dose and day after treatment is significant (two-way ANOVA). S. anthelmia extract could, therefore, find application in the control of helminth in livestock, by the ethnoveterinary medicine approach.

Rather than by direct acquisition via lateral gene transfer, GHF5 cellulases were passed on from early Pratylenchidae to root-knot and cyst nematodes.

PubMed

Rybarczyk-Mydłowska, Katarzyna; Maboreke, Hazel Ruvimbo; van Megen, Hanny; van den Elsen, Sven; Mooyman, Paul; Smant, Geert; Bakker, Jaap; Helder, Johannes

2012-11-21

Plant parasitic nematodes are unusual Metazoans as they are equipped with genes that allow for symbiont-independent degradation of plant cell walls. Among the cell wall-degrading enzymes, glycoside hydrolase family 5 (GHF5) cellulases are relatively well characterized, especially for high impact parasites such as root-knot and cyst nematodes. Interestingly, ancestors of extant nematodes most likely acquired these GHF5 cellulases from a prokaryote donor by one or multiple lateral gene transfer events. To obtain insight into the origin of GHF5 cellulases among evolutionary advanced members of the order Tylenchida, cellulase biodiversity data from less distal family members were collected and analyzed. Single nematodes were used to obtain (partial) genomic sequences of cellulases from representatives of the genera Meloidogyne, Pratylenchus, Hirschmanniella and Globodera. Combined Bayesian analysis of ≈ 100 cellulase sequences revealed three types of catalytic domains (A, B, and C). Represented by 84 sequences, type B is numerically dominant, and the overall topology of the catalytic domain type shows remarkable resemblance with trees based on neutral (= pathogenicity-unrelated) small subunit ribosomal DNA sequences. Bayesian analysis further suggested a sister relationship between the lesion nematode Pratylenchus thornei and all type B cellulases from root-knot nematodes. Yet, the relationship between the three catalytic domain types remained unclear. Superposition of intron data onto the cellulase tree suggests that types B and C are related, and together distinct from type A that is characterized by two unique introns. All Tylenchida members investigated here harbored one or multiple GHF5 cellulases. Three types of catalytic domains are distinguished, and the presence of at least two types is relatively common among plant parasitic Tylenchida. Analysis of coding sequences of cellulases suggests that root-knot and cyst nematodes did not acquire this gene directly

Studying the Symbiotic Bacterium Xenorhabdus nematophila in Individual, Living Steinernema carpocapsae Nematodes Using Microfluidic Systems.

PubMed

Stilwell, Matthew D; Cao, Mengyi; Goodrich-Blair, Heidi; Weibel, Douglas B

2018-01-01

Animal-microbe symbioses are ubiquitous in nature and scientifically important in diverse areas, including ecology, medicine, and agriculture. Steinernema nematodes and Xenorhabdus bacteria compose an established, successful model system for investigating microbial pathogenesis and mutualism. The bacterium Xenorhabdus nematophila is a species-specific mutualist of insect-infecting Steinernema carpocapsae nematodes. The bacterium colonizes a specialized intestinal pocket within the infective stage of the nematode, which transports the bacteria between insects that are killed and consumed by the pair for reproduction. Current understanding of the interaction between the infective-stage nematode and its bacterial colonizers is based largely on population-level, snapshot time point studies on these organisms. This limitation arises because investigating temporal dynamics of the bacterium within the nematode is impeded by the difficulty of isolating and maintaining individual living nematodes and tracking colonizing bacterial cells over time. To overcome this challenge, we developed a microfluidic system that enables us to spatially isolate and microscopically observe individual, living Steinernema nematodes and monitor the growth and development of the associated X. nematophila bacterial communities-starting from a single cell or a few cells-over weeks. Our data demonstrate, to our knowledge, the first direct, temporal, in vivo visual analysis of a symbiosis system and the application of this system to reveal continuous dynamics of the symbiont population in the living host animal. IMPORTANCE This paper describes an experimental system for directly investigating population dynamics of a symbiotic bacterium, Xenorhabdus nematophila , in its host-the infective stage of the entomopathogenic nematode Steinernema carpocapsae . Tracking individual and groups of bacteria in individual host nematodes over days and weeks yielded insight into dynamic growth and topology changes

Previously unrecognized stages of species-specific colonization in the mutualism between Xenorhabdus bacteria and Steinernema nematodes

PubMed Central

Chaston, John M.; Murfin, Kristen E.; Heath-Heckman, Elizabeth A.; Goodrich-Blair, Heidi

2013-01-01

Summary The specificity of a horizontally transmitted microbial symbiosis is often defined by molecular communication between host and microbe during initial engagement, which can occur in discrete stages. In the symbiosis between Steinernema nematodes and Xenorhabdus bacteria, previous investigations focused on bacterial colonization of the intestinal lumen (receptacle) of the nematode infective juvenile (IJ), as this was the only known persistent, intimate, and species-specific contact between the two. Here we show that bacteria colonize the anterior intestinal cells of other nematode developmental stages in a species-specific manner. Also, we describe three processes that only occur in juveniles that are destined to become IJs. First, a few bacterial cells colonize the nematode pharyngeal-intestinal valve (PIV) anterior to the intestinal epithelium. Second, the nematode intestine constricts while bacteria initially remain in the PIV. Third, anterior intestinal constriction relaxes and colonizing bacteria occupy the receptacle. At each stage, colonization requires X. nematophila symbiosis region 1 (SR1) genes and is species-specific: X. szentirmaii, which naturally lacks SR1, does not colonize unless SR1 is ectopically expressed. These findings reveal new aspects of Xenorhabdus bacteria interactions with and transmission by their Steinernema nematode hosts, and demonstrate that bacterial SR1 genes aid in colonizing nematode epithelial surfaces. PMID:23480552

Mechanisms of host seeking by parasitic nematodes.

PubMed

Gang, Spencer S; Hallem, Elissa A

2016-07-01

The phylum Nematoda comprises a diverse group of roundworms that includes parasites of vertebrates, invertebrates, and plants. Human-parasitic nematodes infect more than one billion people worldwide and cause some of the most common neglected tropical diseases, particularly in low-resource countries [1]. Parasitic nematodes of livestock and crops result in billions of dollars in losses each year [1]. Many nematode infections are treatable with low-cost anthelmintic drugs, but repeated infections are common in endemic areas and drug resistance is a growing concern with increasing therapeutic and agricultural administration [1]. Many parasitic nematodes have an environmental infective larval stage that engages in host seeking, a process whereby the infective larvae use sensory cues to search for hosts. Host seeking is a complex behavior that involves multiple sensory modalities, including olfaction, gustation, thermosensation, and humidity sensation. As the initial step of the parasite-host interaction, host seeking could be a powerful target for preventative intervention. However, host-seeking behavior remains poorly understood. Here we review what is currently known about the host-seeking behaviors of different parasitic nematodes, including insect-parasitic nematodes, mammalian-parasitic nematodes, and plant-parasitic nematodes. We also discuss the neural bases of these behaviors. Copyright © 2016 Elsevier B.V. All rights reserved.

Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest.

PubMed

Lambshead, P John D; Brown, Caroline J; Ferrero, Timothy J; Hawkins, Lawrence E; Smith, Craig R; Mitchell, Nicola J

2003-01-09

The possibility for commercial mining of deep-sea manganese nodules is currently under exploration in the abyssal Clarion-Clipperton Fracture Zone. Nematodes have potential for biomonitoring of the impact of commercial activity but the natural biodiversity is unknown. We investigate the feasibility of nematodes as biomonitoring organisms and give information about their natural biodiversity. The taxonomic composition (at family to genus level) of the nematode fauna in the abyssal Pacific is similar, but not identical to, the North Atlantic. Given the immature state of marine nematode taxonomy, it is not possible to comment on the commonality or otherwise of species between oceans. The between basin differences do not appear to be directly linked to current ecological factors. The abyssal Pacific region (including the Fracture Zone) could be divided into two biodiversity subregions that conform to variations in the linked factors of flux to the benthos and of sedimentary characteristics. Richer biodiversity is associated with areas of known phytodetritus input and higher organic-carbon flux. Despite high reported sample diversity, estimated regional diversity is less than 400 species. The estimated regional diversity of the CCFZ is a tractable figure for biomonitoring of commercial activities in this region using marine nematodes, despite the immature taxonomy (i.e. most marine species have not been described) of the group. However, nematode ecology is in dire need of further study.

Wide interguild relationships among entomopathogenic and free-living nematodes in soil as measured by real time qPCR.

PubMed

Campos-Herrera, Raquel; El-Borai, Fahiem E; Duncan, Larry W

2012-10-01

Entomopathogenic nematodes (EPNs) are promising biological control agents of soil-dwelling insect pests of many crops. These nematodes are ubiquitous in both natural and agricultural areas. Their efficacy against arthropods is affected directly and indirectly by food webs and edaphic conditions. It has long been suggested that a greater understanding of EPN ecology is needed to achieve consistent biological control by these nematodes and the development of molecular tools is helping to overcome obstacles to the study of cryptic organisms and complex interactions. Here we extend the repertoire of molecular tools to characterize soil food webs by describing primers/probe set to quantify certain free-living, bactivorous nematodes (FLBNs) that interact with EPNs in soil. Three FLBN isolates were recovered from soil baited with insect larvae. Morphological and molecular characterization confirmed their identities as Acrobeloides maximum (RT-1-R15C and RT-2-R25A) and Rhabditis rainai (PT-R14B). Laboratory experiments demonstrated the ability of these FLBNs to interfere with the development of Steinernema diaprepesi, Steinernema riobrave and Heterorhabditis indica parasitizing the weevil Diaprepes abbreviatus (P<0.001), perhaps due to resource competition. A molecular probe was developed for the strongest competitor, A. maximum. We selected the highly conserved SSU rDNA sequence to design the primers/probe, because these sequences are more abundantly available for free-living nematodes than ITS sequences that can likely provide better taxonomic resolution. Our molecular probe can identify organisms that share ⩾98% similarity at this locus. The use of this molecular probe to characterize soil communities from samples of nematode DNA collected within a citrus orchard revealed positive correlations (P<0.01) between Acrobeloides-group nematodes and total numbers of EPNs (S. diaprepesi, H. indica and Heterorhabditis zealandica) as well as a complex of nematophagous fungi

Transport of Palmitic Acid Across the Tegument of the Entomophilic Nematode Romanomermis culicivorax.

PubMed

Gordon, R; Burford, I R

1984-01-01

Romanomermis culicivorax juveniles, dissected out of Aedes aegypti larvae 7 days after infection, were incubated under controlled conditions in isotonic saline containing (1)C-U-palmitic acid to investigate the nature of the transport mechanism(s) used by the nematode for transcuticular uptake of palmitic acid. Net uptake of the isotope by the nematode was of a logarithmic nature with respect to time. Uptake of palmitic acid was accomplished by a combination of diffusion and a mediated process which was substrate saturable and competitively inhibited by myristic and stearic acids. Both 2,4-dinitrophenol and ouabain inhibited uptake of palmitic acid and thus supported the hypothesis that the carrier system is of the active transport variety and is coupled to a NaK ATPase pump.

Naturally Acquired Mentoring Relationships and Young Adult Outcomes among Adolescents with Learning Disabilities

ERIC Educational Resources Information Center

Ahrens, Kym; DuBois, David Lane; Lozano, Paula; Richardson, Laura P.

2010-01-01

We evaluated whether having a naturally acquired mentor during adolescence was associated with improved adult outcomes among youth with learning disabilities (YLD). Mentored youth were more likely to have graduated from high school, reported a higher level of self-esteem, and reported a higher overall number of positive outcomes than nonmentored…

Nematode communities in sediments of the Kermadec Trench, Southwest Pacific Ocean

NASA Astrophysics Data System (ADS)

Leduc, Daniel; Rowden, Ashley A.

2018-04-01

Hadal trenches are characterized by environmental conditions not found in any other deep-sea environment, such as steep topography and periodic disturbance by turbidity flows, which are likely responsible for the distinct nature of benthic communities of hadal trenches relative to those of the abyssal plain. Nematodes are the most abundant metazoans in the deep-sea benthos, but it is not yet clear if different trenches host distinct nematode communities, and no data are yet available on the communities of most trenches, including the Kermadec Trench in the Southwest Pacific. Quantitative core samples from the seafloor of the Kermadec Trench were recently obtained from four sites at 6000-9000 m depth which allowed for analyses of meiofauna, and nematodes in particular, for the first time. Nematode community and trophic structure was also compared with other trenches using published data. There was a bathymetric gradient in meiofauna abundance, biomass, and community structure within the Kermadec Trench, but patterns for species richness were ambiguous depending on which metric was used. There was a change in community structure from shallow to deep sites, as well as a consistent change in community structure from the upper sediment layers to the deeper sediment layers across the four sites. These patterns are most likely explained by variation in food availability within the trench, and related to trench topography. Together, deposit and microbial feeders represented 48-92% of total nematode abundance in the samples, which suggests that fine organic detritus and bacteria are major food sources. The relatively high abundance of epigrowth feeders at the 6000 and 9000 m sites (38% and 31%, respectively) indicates that relatively freshly settled microalgal cells represent another important food source at these sites. We found a significant difference in species community structure between the Kermadec and Tonga trenches, which was due to both the presence/absence of

Parasitic Nematode Immunomodulatory Strategies: Recent Advances and Perspectives

PubMed Central

Cooper, Dustin; Eleftherianos, Ioannis

2016-01-01

More than half of the described species of the phylum Nematoda are considered parasitic, making them one of the most successful groups of parasites. Nematodes are capable of inhabiting a wide variety of niches. A vast array of vertebrate animals, insects, and plants are all identified as potential hosts for nematode parasitization. To invade these hosts successfully, parasitic nematodes must be able to protect themselves from the efficiency and potency of the host immune system. Innate immunity comprises the first wave of the host immune response, and in vertebrate animals it leads to the induction of the adaptive immune response. Nematodes have evolved elegant strategies that allow them to evade, suppress, or modulate host immune responses in order to persist and spread in the host. Nematode immunomodulation involves the secretion of molecules that are capable of suppressing various aspects of the host immune response in order to promote nematode invasion. Immunomodulatory mechanisms can be identified in parasitic nematodes infecting insects, plants, and mammals and vary greatly in the specific tactics by which the parasites modify the host immune response. Nematode-derived immunomodulatory effects have also been shown to affect, negatively or positively, the outcome of some concurrent diseases suffered by the host. Understanding nematode immunomodulatory actions will potentially reveal novel targets that will in turn lead to the development of effective means for the control of destructive nematode parasites. PMID:27649248

Parasitic Nematode Immunomodulatory Strategies: Recent Advances and Perspectives.

PubMed

Cooper, Dustin; Eleftherianos, Ioannis

2016-09-14

More than half of the described species of the phylum Nematoda are considered parasitic, making them one of the most successful groups of parasites. Nematodes are capable of inhabiting a wide variety of niches. A vast array of vertebrate animals, insects, and plants are all identified as potential hosts for nematode parasitization. To invade these hosts successfully, parasitic nematodes must be able to protect themselves from the efficiency and potency of the host immune system. Innate immunity comprises the first wave of the host immune response, and in vertebrate animals it leads to the induction of the adaptive immune response. Nematodes have evolved elegant strategies that allow them to evade, suppress, or modulate host immune responses in order to persist and spread in the host. Nematode immunomodulation involves the secretion of molecules that are capable of suppressing various aspects of the host immune response in order to promote nematode invasion. Immunomodulatory mechanisms can be identified in parasitic nematodes infecting insects, plants, and mammals and vary greatly in the specific tactics by which the parasites modify the host immune response. Nematode-derived immunomodulatory effects have also been shown to affect, negatively or positively, the outcome of some concurrent diseases suffered by the host. Understanding nematode immunomodulatory actions will potentially reveal novel targets that will in turn lead to the development of effective means for the control of destructive nematode parasites.

The first record of entomopathogenic nematodes (Rhabiditiae: Steinernematidae and Heterorhabditidae) in natural ecosystems in Lebanon: A biogeographic approach in the Mediterranean region.

PubMed

Noujeim, Elise; Khater, Carla; Pages, Sylvie; Ogier, Jean-Claude; Tailliez, Patrick; Hamze, Mouïn; Thaler, Olivier

2011-05-01

A survey of entomopathogenic nematodes in Lebanon was conducted for the first time during 2008-2009. Samples were collected on the coastal strip and in nine vegetation types extending from the coastal line to 3088m above sea level. Wooded and herbaceous ecosystems were considered for sampling purposes. A total of 570 samples were taken, out of which 1% were positive for entomopathogenic nematodes. Approximately, 15.8% out of the 19 sites sampled revealed entomopathogenic nematodes presence (representing three samples). Two entomopathogenic nematodes species Heterorhabditis bacteriophora and Steinernema feltiae were recovered, and identification of their symbiotic bacteria revealed the presence of a Xenorhabdus bovienii, Photorhabdus temperata subsp. thracensis, Photorhabdus luminescens subsp. kayaii and Photorhabdus luminescens subsp. Laumondii. Copyright © 2011 Elsevier Inc. All rights reserved.

Susceptibility of Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae) to Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae and Steinernematidae)

PubMed Central

Tourtois, Joseph; Grieshop, Matthew J.

2015-01-01

Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae) and entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Steinernematidae) are two soil-dwelling biological control agents used to manage western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) and fungus gnats Bradysis spp. (Diptera: Sciaridae) in glasshouses. Growers often use multiple natural enemies to achieve economic control, but knowledge of interactions among natural enemies is lacking. We conducted a laboratory bioassay to test the pathogenicity of four commercially available nematode species—Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhbditidae), Steinernema carpocapsae (Weiser) (Rhabditida: Steinernematidae), S. feltiae (Filipjev), and S. riobrave Cabanillas et al.—to third instar and adult D. coriaria. Third instars were three times more susceptible than the adults to the entomopathogenic nematodes. Mortality for D. coriaria adults and third instars treated with S. feltiae and H. bacteriophora was lower than the mortality for D. coriaria adults and third instars treated with S. carpocapsae and S. riobrave. Neither infective juvenile foraging behavior nor size correlates with D. coriaria mortality. Dalotia coriaria appears to be most likely compatible with applications of S. feltiae and H. bacteriophora. PMID:26463077

Entomopathogenic nematodes for the biocontrol of ticks.

PubMed

Samish, M; Glazer, I

2001-08-01

Entomopathogenic steinemematid and heterorhabditid nematodes are increasingly used to control insect pests of economically important crops. Laboratory and field simulation trials show that ticks are also susceptible to these nematodes. The authors review the potential of entomogenous nematodes for the control of ticks.

Controlling gastrointestinal nematodes in cattle by Bacillus species.

PubMed

Pinto, Natália Berne; de Castro, Leonardo Mortagua; de Almeida Capella, Gabriela; Motta, Tairan Ourique; de Souza Stori de Lara, Ana Paula; de Moura, Micaele Quintana; Berne, Maria Elisabeth Aires; Leite, Fábio Pereira Leivas

2017-10-15

In this study, we tested the in vitro and in vivo larvicidal activity of Bacillus species against gastrointestinal nematodes in cattle, and their viability in the presence of anthelmintics. For in vitro tests, cattle feces naturally infected with trichostrongylides were incubated with spore suspensions of Bacillus circulans (Bcir), B. thuringiensis var. osvaldocruzi (Bto), B. thuringiensis var. israelensis (Bti) or B. thuringiensis var. kurstaki (Btk). Subsequently, residual larvae were counted and identified. All of the Bacillus species showed 60% or more larvicidal effects. Bcir and Bti were selected to be incubated with anthelmintics (moxidectin, nitroxynil and levamisole), and after 24, 72, and 144h, their viability was evaluated. Bti showed highest drug resistance, maintaining a concentration of 1×10 7 CFU/mL. Based on this result, Bti was selected for in vivo tests on calves naturally infected with gastrointestinal nematodes. The calves were dived into four groups: Group 1, Bti suspension of ∼1×10 9 CFU orally administered; Group 2, Bti suspension of ∼1×10 9 CFU orally administered with levamisole (subcutaneously, 150mg); Group 3, only levamisole (subcutaneously, 150mg), and Group 4 untreated. Then 24 and 48h after treatment, larvae numbers were counted. We observed a reduction of 84%, 100%, and 100% after 48h of treatment, respectively, for Groups 1, 2 and 3 treatments in comparison with the untreated. The tested Bacillus species showed larvicidal activity against bovine trichostrongylides, and its association with anthelmintics. It may serve as a promising integrated alternative for control of gastrointestinal nematodes in cattle. Copyright © 2017 Elsevier B.V. All rights reserved.

Top 10 plant-parasitic nematodes in molecular plant pathology.

PubMed

Jones, John T; Haegeman, Annelies; Danchin, Etienne G J; Gaur, Hari S; Helder, Johannes; Jones, Michael G K; Kikuchi, Taisei; Manzanilla-López, Rosa; Palomares-Rius, Juan E; Wesemael, Wim M L; Perry, Roland N

2013-12-01

The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a 'top 10' list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly. © 2013 BSPP AND JOHN WILEY & SONS LTD.

Host-finding behaviour in the nematode Pristionchus pacificus.

PubMed

Brown, Federico D; D'Anna, Isabella; Sommer, Ralf J

2011-11-07

Costs and benefits of foraging have been studied in predatory animals. In nematodes, ambushing or cruising behaviours represent adaptations that optimize foraging strategies for survival and host finding. A behaviour associated with host finding of ambushing nematode dauer juveniles is a sit-and-wait behaviour, otherwise known as nictation. Here, we test the function of nictation by relating occurrence of nictation in Pristionchus pacificus dauer juveniles to the ability to attach to laboratory host Galleria mellonella. We used populations of recently isolated and mutagenized laboratory strains. We found that nictation can be disrupted using a classical forward genetic approach and characterized two novel nictation-defective mutant strains. We identified two recently isolated strains from la Réunion island, one with a higher proportion of nictating individuals than the laboratory strain P. pacificus PS312. We found a positive correlation between nictation frequencies and host attachment in these strains. Taken together, our combination of genetic analyses with natural variation studies presents a new approach to the investigation of behavioural and ecological functionality. We show that nictation behaviour in P. pacificus nematodes serves as a host-finding behaviour. Our results suggest that nictation plays a role in the evolution of new life-history strategies, such as the evolution of parasitism.

Nematode community structure in a vineyard soil.

PubMed

Ferris, H; McKenry, M V

1976-04-01

Distribution of the nematode community in a California vineyard was studied over a 13-month period. Omnivorous and microbivorous nematodes were similarly distributed in the root zone, with greatest densities occurring between vine rows and near the soil surface. Greatest densities of plant-parasitic nematodes were found in the vine row, with the individual species differing in their vertical distribution. Total nematode biomass was greatest between rows near the surface. Biomass of plant parasites was greatest in the upper 30 cm of soil in the row, whereas biomass of microbivores was greatest in this region between rows. Of the plant-parasitic nematodes, the variability in distribution among vines was greatest for Paratylenchus hamatus and least for Meloidogyne spp.

ORGANIC VS CONVENTIONAL: SOIL NEMATODE COMMUNITY STRUCTURE AND FUNCTION.

PubMed

Kapp, C; Storey, S G; Malan, A P

2014-01-01

Global increases in human population are creating an ever-greater need for food production. Poor soil management practices have degraded soil to such an extent that rapidly improved management practices is the only way to ensure future food demands. In South Africa, deciduous fruit producers are realising the need for soil health, and for an increased understanding of the benefits of soil ecology, to ensure sustainable fruit production. This depends heavily on improved orchard management. Conventional farming relies on the addition of artificial fertilizers, and the application of chemicals, to prevent or minimise, the effects of the soil stages of pest insects, and of plant-parasitic nematodes. Currently, there is resistance toward conventional farming practices, which, it is believed, diminishes biodiversity within the soil. The study aimed to establish the soil nematode community structure and function in organically, and conventionally, managed deciduous fruit orchards. This was done by determining the abundance, the diversity, and the functionality of the naturally occurring free-living, and plant-parasitic, nematodes in deciduous fruit orchards in the Western Cape province of South Africa. The objective of the study was to form the basis for the use of nematodes as future indicators of soil health in deciduous fruit orchards. Orchards from neighbouring organic, and conventional, apricot farms, and from an organic apple orchard, were studied. All the nematodes were quantified, and identified, to family level. The five nematode-classified trophic groups were found at each site, while 14 families were identified in each orchard, respectively. Herbivores were dominant in all the orchards surveyed. Organic apples had the fewest herbivores and fungivores, with the highest number of carnivores. When comparing organic with conventional apricot orchards, higher numbers of plant-parasitic nematodes were found in the organic apricot orchards. The Maturity Index (MI

Social networks of educated nematodes

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes are obligate lethal parasitoids of insect larvae that navigate a chemically complex belowground environment while interacting with their insect hosts, plants, and each other. In this environment, prior exposure to volatile compounds appears to prime nematodes in a compound...

Resource utilization and trophic position of nematodes and harpacticoid copepods in and adjacent to Zostera noltii beds

NASA Astrophysics Data System (ADS)

Vafeiadou, A.-M.; Materatski, P.; Adão, H.; De Troch, M.; Moens, T.

2014-01-01

This study examines the resource use and trophic position of nematodes and harpacticoid copepods at the genus/species level in an estuarine food web in Zostera noltii beds and in adjacent bare sediments, using the natural abundance of stable carbon and nitrogen isotopes. Microphytobenthos is among the main resources of most taxa, but seagrass-associated resources (i.e. seagrass detritus and epiphytes) also contribute to meiobenthos nutrition, with seagrass detritus being available also in deeper sediments and in unvegetated patches close to seagrass beds. A predominant dependence on chemoautotrophic bacteria was demonstrated for the nematode genus Terschellingia and the copepod family Cletodidae. A predatory feeding mode is illustrated for Paracomesoma and other Comesomatidae, which were previously considered first-level consumers (deposit feeders) according to their buccal morphology. The considerable variation found in both resource use and trophic level among nematode genera from the same feeding type, and even among congeneric nematode species, shows that interpretation of nematode feeding ecology based purely on mouth morphology should be avoided.

Radiation Effects on Nematodes: Results from IML-1 Esperiments

NASA Technical Reports Server (NTRS)

Nelson, G. A.; Schubert, W. W.; Kazarians, G. A.; Righards, G. F.; Benton, E. V; Benton, E. R.; Henke, R.

1993-01-01

The nematode Caenorhabditis elegans was exposed to natural space radiation using the ESA Biorack facility aboard Spacelab on International Microgravity Laboratory 1, STS-42. For the major experimental objective dormant animals were suspended in buffer or on agar or immobilized next to CR-39 plactic nuclear track detectors to correlate fluence of HZE particles with genetic events.

Integrated Metabolomics and Morphogenesis Reveal Volatile Signaling of the Nematode-Trapping Fungus Arthrobotrys oligospora.

PubMed

Wang, Bai-Le; Chen, Yong-Hong; He, Jia-Ning; Xue, Hua-Xi; Yan, Ni; Zeng, Zhi-Jun; Bennett, Joan W; Zhang, Ke-Qin; Niu, Xue-Mei

2018-05-01

The adjustment of metabolic patterns is fundamental to fungal biology and plays vital roles in adaptation to diverse ecological challenges. Nematode-trapping fungi can switch their lifestyle from saprophytic to pathogenic by developing specific trapping devices induced by nematodes to infect their prey as a response to nutrient depletion in nature. However, the chemical identity of the specific fungal metabolites used during the switch remains poorly understood. We hypothesized that these important signal molecules might be volatile in nature. Gas chromatography-mass spectrometry was used to carry out comparative analysis of fungal metabolomics during the saprophytic and pathogenic lifestyles of the model species Arthrobotrys oligospora Two media commonly used in research on this species, cornmeal agar (CMA) and potato dextrose agar (PDA), were chosen for use in this study. The fungus produced a small group of volatile furanone and pyrone metabolites that were associated with the switch from the saprophytic to the pathogenic stage. A. oligospora fungi grown on CMA tended to produce more traps and employ attractive furanones to improve the utilization of traps, while fungi grown on PDA developed fewer traps and used nematode-toxic furanone metabolites to compensate for insufficient traps. Another volatile pyrone metabolite, maltol, was identified as a morphological regulator for enhancing trap formation. Deletion of the gene AOL_s00079g496 in A. oligospora led to increased amounts of the furanone attractant (2-fold) in mutants and enhanced the attractive activity (1.5-fold) of the fungus, while it resulted in decreased trap formation. This investigation provides new insights regarding the comprehensive tactics of fungal adaptation to environmental stress, integrating both morphological and metabolomic mechanisms. IMPORTANCE Nematode-trapping fungi are a unique group of soil-living fungi that can switch from the saprophytic to the pathogenic lifestyle once they come

Integrated Metabolomics and Morphogenesis Reveal Volatile Signaling of the Nematode-Trapping Fungus Arthrobotrys oligospora

PubMed Central

Wang, Bai-Le; Chen, Yong-Hong; He, Jia-Ning; Xue, Hua-Xi; Yan, Ni; Zeng, Zhi-Jun; Bennett, Joan W.

2018-01-01

ABSTRACT The adjustment of metabolic patterns is fundamental to fungal biology and plays vital roles in adaptation to diverse ecological challenges. Nematode-trapping fungi can switch their lifestyle from saprophytic to pathogenic by developing specific trapping devices induced by nematodes to infect their prey as a response to nutrient depletion in nature. However, the chemical identity of the specific fungal metabolites used during the switch remains poorly understood. We hypothesized that these important signal molecules might be volatile in nature. Gas chromatography-mass spectrometry was used to carry out comparative analysis of fungal metabolomics during the saprophytic and pathogenic lifestyles of the model species Arthrobotrys oligospora. Two media commonly used in research on this species, cornmeal agar (CMA) and potato dextrose agar (PDA), were chosen for use in this study. The fungus produced a small group of volatile furanone and pyrone metabolites that were associated with the switch from the saprophytic to the pathogenic stage. A. oligospora fungi grown on CMA tended to produce more traps and employ attractive furanones to improve the utilization of traps, while fungi grown on PDA developed fewer traps and used nematode-toxic furanone metabolites to compensate for insufficient traps. Another volatile pyrone metabolite, maltol, was identified as a morphological regulator for enhancing trap formation. Deletion of the gene AOL_s00079g496 in A. oligospora led to increased amounts of the furanone attractant (2-fold) in mutants and enhanced the attractive activity (1.5-fold) of the fungus, while it resulted in decreased trap formation. This investigation provides new insights regarding the comprehensive tactics of fungal adaptation to environmental stress, integrating both morphological and metabolomic mechanisms. IMPORTANCE Nematode-trapping fungi are a unique group of soil-living fungi that can switch from the saprophytic to the pathogenic lifestyle once

The bacterial community of entomophilic nematodes and host beetles.

PubMed

Koneru, Sneha L; Salinas, Heilly; Flores, Gilberto E; Hong, Ray L

2016-05-01

Insects form the most species-rich lineage of Eukaryotes and each is a potential host for organisms from multiple phyla, including fungi, protozoa, mites, bacteria and nematodes. In particular, beetles are known to be associated with distinct bacterial communities and entomophilic nematodes. While entomopathogenic nematodes require symbiotic bacteria to kill and reproduce inside their insect hosts, the microbial ecology that facilitates other types of nematode-insect associations is largely unknown. To illuminate detailed patterns of the tritrophic beetle-nematode-bacteria relationship, we surveyed the nematode infestation profiles of scarab beetles in the greater Los Angeles area over a five-year period and found distinct nematode infestation patterns for certain beetle hosts. Over a single season, we characterized the bacterial communities of beetles and their associated nematodes using high-throughput sequencing of the 16S rRNA gene. We found significant differences in bacterial community composition among the five prevalent beetle host species, independent of geographical origin. Anaerobes Synergistaceae and sulphate-reducing Desulfovibrionaceae were most abundant in Amblonoxia beetles, while Enterobacteriaceae and Lachnospiraceae were common in Cyclocephala beetles. Unlike entomopathogenic nematodes that carry bacterial symbionts, insect-associated nematodes do not alter the beetles' native bacterial communities, nor do their microbiomes differ according to nematode or beetle host species. The conservation of Diplogastrid nematodes associations with Melolonthinae beetles and sulphate-reducing bacteria suggests a possible link between beetle-bacterial communities and their associated nematodes. Our results establish a starting point towards understanding the dynamic interactions between soil macroinvertebrates and their microbiota in a highly accessible urban environment. © 2016 John Wiley & Sons Ltd.

Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

PubMed

Zhou, Jiao; Zhao, Li-Lin; Yu, Hai-Ying; Wang, Yan-Hong; Zhang, Wei; Hu, Song-Nian; Zou, Zhen; Sun, Jiang-Hua

2018-04-02

Immune response of insect vectors to transmitted pathogens or insect hosts against parasites are well studied, whereas the mechanism of tripartite interactions remains elusive. In this study, we investigated the immune interactions of the vector beetle Monochamus alternatus ( Ma) to the devastating plant parasitic nematode Bursaphelenchus xylophilus ( Bx) and the insect parasitic nematode Howardula phyllotretae ( Hp). We report the unique immune mechanism by which the vector beetle tolerates many devastating Bx in its trachea, yet that immune tolerance is compromised by the parasitic nematode Hp. Contact with either nematode species triggers epithelial reactive oxygen species (ROS) production in Ma. Only the entry of Bx, not Hp, infection, induces increased expression of antioxidative genes, through which the ROS levels are balanced in the trachea of beetles. Furthermore, we found that up-regulation of antioxidative genes was induced by the interaction of Toll receptors. In contrast, beetles infected by Hp retain high levels of oxidative stress and melanization in trachea, and as a result, decrease Bx loading. This study highlights the role of Toll receptors in mediating the activation of antioxidative genes in immune tolerance to plant parasitic nematodes, and suggests the use of insect parasites as a biologic control.-Zhou, J., Zhao, L.-L., Yu, H.-Y., Wang, Y.-H., Zhang, W., Hu, S.-N., Zou, Z., Sun, J.-H. Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

Plant species richness sustains higher trophic levels of soil nematode communities after consecutive environmental perturbations.

PubMed

Cesarz, Simone; Ciobanu, Marcel; Wright, Alexandra J; Ebeling, Anne; Vogel, Anja; Weisser, Wolfgang W; Eisenhauer, Nico

2017-07-01

The magnitude and frequency of extreme weather events are predicted to increase in the future due to ongoing climate change. In particular, floods and droughts resulting from climate change are thought to alter the ecosystem functions and stability. However, knowledge of the effects of these weather events on soil fauna is scarce, although they are key towards functioning of terrestrial ecosystems. Plant species richness has been shown to affect the stability of ecosystem functions and food webs. Here, we used the occurrence of a natural flood in a biodiversity grassland experiment that was followed by a simulated summer drought experiment, to investigate the interactive effects of plant species richness, a natural flood, and a subsequent summer drought on nematode communities. Three and five months after the natural flooding, effects of flooding severity were still detectable in the belowground system. We found that flooding severity decreased soil nematode food-web structure (loss of K-strategists) and the abundance of plant feeding nematodes. However, high plant species richness maintained higher diversity and abundance of higher trophic levels compared to monocultures throughout the flood. The subsequent summer drought seemed to be of lower importance but reversed negative flooding effects in some cases. This probably occurred because the studied grassland system is well adapted to drought, or because drought conditions alleviated the negative impact of long-term soil waterlogging. Using soil nematodes as indicator taxa, this study suggests that high plant species richness can maintain soil food web complexity after consecutive environmental perturbations.

Evolution of Parasitism in Insect-transmitted Plant Nematodes

PubMed Central

Giblin-Davis, R. M.; Davies, K. A.; Morris, K.; Thomas, W. K.

2003-01-01

Nematode-insect associations have evolved many times in the phylum Nematoda, but these lineages involve plant parasitism only in the Secernentean orders Aphelenchida and Tylenchida. In the Aphelenchida (Aphelenchoidoidea), Bursaphelenchus xylophilus (Pine wood nematode), B. cocophilus (Red ring or Coconut palm nematode) (Parasitaphelenchidae), and the many potential host-specific species of Schistonchus (fig nematodes) (Aphelenchoididae) nematode-insect interactions probably evolved independently from dauer-forming, mycophagous ancestors that were phoretically transmitted to breeding sites of their insect hosts in plants. Mycophagy probably gave rise to facultative or obligate plant-parasitism because of opportunities due to insect host switches or peculiarities in host behavior. In the Tylenchida, there is one significant radiation of insect-associated plant parasites involving Fergusobia nematodes (Fergusobiinae: Neotylenchidae) and Fergusonina (Fergusoninidae) flies as mutualists that gall myrtaceous plant buds or leaves. These dicyclic nematodes have different phases that are parasitic in either the insect or the plant hosts. The evolutionary origin of this association is unclear. PMID:19265987

Loss of the insulator protein CTCF during nematode evolution

PubMed Central

Heger, Peter; Marin, Birger; Schierenberg, Einhard

2009-01-01

Background The zinc finger (ZF) protein CTCF (CCCTC-binding factor) is highly conserved in Drosophila and vertebrates where it has been shown to mediate chromatin insulation at a genomewide level. A mode of genetic regulation that involves insulators and insulator binding proteins to establish independent transcriptional units is currently not known in nematodes including Caenorhabditis elegans. We therefore searched in nematodes for orthologs of proteins that are involved in chromatin insulation. Results While orthologs for other insulator proteins were absent in all 35 analysed nematode species, we find orthologs of CTCF in a subset of nematodes. As an example for these we cloned the Trichinella spiralis CTCF-like gene and revealed a genomic structure very similar to the Drosophila counterpart. To investigate the pattern of CTCF occurrence in nematodes, we performed phylogenetic analysis with the ZF protein sets of completely sequenced nematodes. We show that three ZF proteins from three basal nematodes cluster together with known CTCF proteins whereas no zinc finger protein of C. elegans and other derived nematodes does so. Conclusion Our findings show that CTCF and possibly chromatin insulation are present in basal nematodes. We suggest that the insulator protein CTCF has been secondarily lost in derived nematodes like C. elegans. We propose a switch in the regulation of gene expression during nematode evolution, from the common vertebrate and insect type involving distantly acting regulatory elements and chromatin insulation to a so far poorly characterised mode present in more derived nematodes. Here, all or some of these components are missing. Instead operons, polycistronic transcriptional units common in derived nematodes, seemingly adopted their function. PMID:19712444

Biocontrol of ticks by entomopathogenic nematodes. Research update.

PubMed

Samish, M; Alekseev, E; Glazer, I

2000-01-01

Entomopathogenic nematodes (EPNs) are lethal to ticks even though they do not use their normal propagation cycle within tick cadavers. The tick Boophilus annulatus was found to be far more susceptible to EPNs than Hyalomma excavatum, Rhipicephalus bursa, or Rhipicephalus sanguineus. Ticks seem to be less susceptible to nematodes when feeding on a host. Preimaginal tick stages were less susceptible to nematodes than adult ticks. The mortality rate of unfed females was highest, followed by unfed males, and engorged females. The virulence of nematodes to ticks varied greatly among different nematode strains. In most cases, the Heterorhabditis sp. strains were the most virulent strains tested in petri dishes. In buckets containing sandy soil sprayed with 50 nematodes/cm2 and engorged B. annulatus females, the LT50 of the ticks was less than five days. The addition of manure to soil or a manure extract to petri dishes reduced nematode virulence. Since ticks spend most of their life cycle in the upper humid layer of the ground, and many nematode strains share this same ecological niche, the use of EPNs for biocontrol of ticks appears promising.

Nematode neuropeptides as transgenic nematicides

PubMed Central

Patten, Cheryl; Fleming, Colin C.; Maule, Aaron G.

2017-01-01

Plant parasitic nematodes (PPNs) seriously threaten global food security. Conventionally an integrated approach to PPN management has relied heavily on carbamate, organophosphate and fumigant nematicides which are now being withdrawn over environmental health and safety concerns. This progressive withdrawal has left a significant shortcoming in our ability to manage these economically important parasites, and highlights the need for novel and robust control methods. Nematodes can assimilate exogenous peptides through retrograde transport along the chemosensory amphid neurons. Peptides can accumulate within cells of the central nerve ring and can elicit physiological effects when released to interact with receptors on adjoining cells. We have profiled bioactive neuropeptides from the neuropeptide-like protein (NLP) family of PPNs as novel nematicides, and have identified numerous discrete NLPs that negatively impact chemosensation, host invasion and stylet thrusting of the root knot nematode Meloidogyne incognita and the potato cyst nematode Globodera pallida. Transgenic secretion of these peptides from the rhizobacterium, Bacillus subtilis, and the terrestrial microalgae Chlamydomonas reinhardtii reduce tomato infection levels by up to 90% when compared with controls. These data pave the way for the exploitation of nematode neuropeptides as a novel class of plant protective nematicide, using novel non-food transgenic delivery systems which could be deployed on farmer-preferred cultivars. PMID:28241060

Interspecific nematode signals regulate dispersal behavior.

PubMed

Kaplan, Fatma; Alborn, Hans T; von Reuss, Stephan H; Ajredini, Ramadan; Ali, Jared G; Akyazi, Faruk; Stelinski, Lukasz L; Edison, Arthur S; Schroeder, Frank C; Teal, Peter E

2012-01-01

Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs. Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers. Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes.

Strawberry Cultivars Vary in their Resistance to Northern Lesion Nematode

PubMed Central

Dale, Adam; Potter, John W.

1998-01-01

The genetic diversity of commercial cultivars of strawberry Fragaria x ananassa from various parentages, as expressed by their resistance to the northem lesion nematode Pratylenchus penetrans, was evaluated in nematode-infested field plots for two growing seasons. Data taken for each plant in each season included soil nematode Pi and Pf, end-of-season nematode numbers in each entire root system, and end-of-season fresh and dry top weight and whole root system weight. Resistance was estimated using an index of the nematode load on the plant: Nematode load = {n(root) + (200 × n[soil])}/{root dry weight} where n (root) = number of nematodes in the root, n [soil] = number of nematodes in 50 g of nonfumigated soil, and 200 is a multiplier to convert the soil nematode count to a 10-kg basis. Nineteen strawberry cultivars varied in their resistance to the northern lesion nematode, from a mean load of 382 nematodes/plant for Pajaro to 1,818 nematodes/plant for Veestar. This variability could be related to the original family groupings, with the most resistant cultivars related to Lassen and the least resistant to Sparkle x Valentine. PMID:19274249

Unexpected Variation in Neuroanatomy among Diverse Nematode Species

PubMed Central

Han, Ziduan; Boas, Stephanie; Schroeder, Nathan E.

2016-01-01

Nematodes are considered excellent models for understanding fundamental aspects of neuron function. However, nematodes are less frequently used as models for examining the evolution of nervous systems. While the habitats and behaviors of nematodes are diverse, the neuroanatomy of nematodes is often considered highly conserved. A small number of nematode species greatly influences our understanding of nematode neurobiology. The free-living species Caenorhabditis elegans and, to a lesser extent, the mammalian gastrointestinal parasite Ascaris suum are, historically, the primary sources of knowledge regarding nematode neurobiology. Despite differences in size and habitat, C. elegans and A. suum share a surprisingly similar neuroanatomy. Here, we examined species across several clades in the phylum Nematoda and show that there is a surprising degree of neuroanatomical variation both within and among nematode clades when compared to C. elegans and Ascaris. We found variation in the numbers of neurons in the ventral nerve cord and dye-filling pattern of sensory neurons. For example, we found that Pristionchus pacificus, a bacterial feeding species used for comparative developmental research had 20% fewer ventral cord neurons compared to C. elegans. Steinernema carpocapsae, an insect-parasitic nematode capable of jumping behavior, had 40% more ventral cord neurons than C. elegans. Interestingly, the non-jumping congeneric nematode, S. glaseri showed an identical number of ventral cord neurons as S. carpocapsae. There was also variability in the timing of neurodevelopment of the ventral cord with two of five species that hatch as second-stage juveniles showing delayed neurodevelopment. We also found unexpected variation in the dye-filling of sensory neurons among examined species. Again, sensory neuron dye-filling pattern did not strictly correlate with phylogeny. Our results demonstrate that variation in nematode neuroanatomy is more prevalent than previously assumed and

Nematode CLE signaling in Arabidopsis requires CLAVATA2 and CORYNE.

PubMed

Replogle, Amy; Wang, Jianying; Bleckmann, Andrea; Hussey, Richard S; Baum, Thomas J; Sawa, Shinichiro; Davis, Eric L; Wang, Xiaohong; Simon, Rüdiger; Mitchum, Melissa G

2011-02-01

Plant-parasitic cyst nematodes secrete CLAVATA3 (CLV3)/ESR (CLE)-like effector proteins. These proteins have been shown to act as ligand mimics of plant CLE peptides and are required for successful nematode infection; however, the receptors for nematode CLE-like peptides have not been identified. Here we demonstrate that CLV2 and CORYNE (CRN), members of the receptor kinase family, are required for nematode CLE signaling. Exogenous peptide assays and overexpression of nematode CLEs in Arabidopsis demonstrated that CLV2 and CRN are required for perception of nematode CLEs. In addition, promoter-reporter assays showed that both receptors are expressed in nematode-induced syncytia. Lastly, infection assays with receptor mutants revealed a decrease in both nematode infection and syncytium size. Taken together, our results indicate that perception of nematode CLEs by CLV2 and CRN is not only required for successful nematode infection but is also involved in the formation and/or maintenance of nematode-induced syncytia. © 2010 The Authors. The Plant Journal © 2010 Blackwell Publishing Ltd.

Entomopathogenic nematode food webs in an ancient, mining pollution gradient in Spain.

PubMed

Campos-Herrera, Raquel; Rodríguez Martín, José Antonio; Escuer, Miguel; García-González, María Teresa; Duncan, Larry W; Gutiérrez, Carmen

2016-12-01

Mining activities pollute the environment with by-products that cause unpredictable impacts in surrounding areas. Cartagena-La Unión mine (Southeastern-Spain) was active for >2500years. Despite its closure in 1991, high concentrations of metals and waste residues remain in this area. A previous study using nematodes suggested that high lead content diminished soil biodiversity. However, the effects of mine pollution on specific ecosystem services remain unknown. Entomopathogenic nematodes (EPN) play a major role in the biocontrol of insect pests. Because EPNs are widespread throughout the world, we speculated that EPNs would be present in the mined areas, but at increased incidence with distance from the pollution focus. We predicted that the natural enemies of nematodes would follow a similar spatial pattern. We used qPCR techniques to measure abundance of five EPN species, five nematophagous fungi species, two bacterial ectoparasites of EPNs and one group of free-living nematodes that compete for the insect-cadaver. The study comprised 193 soil samples taken from mining sites, natural areas and agricultural fields. The highest concentrations of iron and zinc were detected in the mined area as was previously described for lead, cadmium and nickel. Molecular tools detected very low numbers of EPNs in samples found to be negative by insect-baiting, demonstrating the importance of the approach. EPNs were detected at low numbers in 13% of the localities, without relationship to heavy-metal concentrations. Only Acrobeloides-group nematodes were inversely related to the pollution gradient. Factors associated with agricultural areas explained 98.35% of the biotic variability, including EPN association with agricultural areas. Our study suggests that EPNs have adapted to polluted habitats that might support arthropod hosts. By contrast, the relationship between abundance of Acrobeloides-group and heavy-metal levels, revealed these taxa as especially well suited bio

Pine wood nematode, Bursaphelenchus xylophilus.

PubMed

Futai, Kazuyoshi

2013-01-01

After devastating vast areas of pine forests in Asian countries, the pine wilt disease spread into European forests in 1999 and is causing worldwide concern. This disease involves very complicated interactions between a pathogenic nematode, its vector beetle, host pine species, and fungi in dead hosts. Pathogenicity of the pine wood nematode is determined not only by its physical and chemical traits but also by its behavioral traits. Most life history traits of the pine wood nematode, such as its phoretic relationship with vector beetles, seem to be more effective in virulent than in avirulent isolates or species. As the pathogenicity determinants, secreted enzymes, and surface coat proteins are very important, they have therefore been studied intensively. The mechanism of quick death of a large pine tree as a result of infection by a tiny nematode could be ascribed to the dysfunction of the water-conducting system caused by the death of parenchyma cells, which must have originally evolved as an inherent resistant system.

Transgenic Potatoes for Potato Cyst Nematode Control Can Replace Pesticide Use without Impact on Soil Quality

PubMed Central

Lilley, Catherine J.; Urwin, Peter E.; Atkinson, Howard J.

2012-01-01

Current and future global crop yields depend upon soil quality to which soil organisms make an important contribution. The European Union seeks to protect European soils and their biodiversity for instance by amending its Directive on pesticide usage. This poses a challenge for control of Globodera pallida (a potato cyst nematode) for which both natural resistance and rotational control are inadequate. One approach of high potential is transgenically based resistance. This work demonstrates the potential in the field of a new transgenic trait for control of G. pallida that suppresses root invasion. It also investigates its impact and that of a second transgenic trait on the non-target soil nematode community. We establish that a peptide that disrupts chemoreception of nematodes without a lethal effect provides resistance to G. pallida in both a containment and a field trial when precisely targeted under control of a root tip-specific promoter. In addition we combine DNA barcoding and quantitative PCR to recognise nematode genera from soil samples without microscope-based observation and use the method for nematode faunal analysis. This approach establishes that the peptide and a cysteine proteinase inhibitor that offer distinct bases for transgenic plant resistance to G. pallida do so without impact on the non-target nematode soil community. PMID:22359559

Transgenic potatoes for potato cyst nematode control can replace pesticide use without impact on soil quality.

PubMed

Green, Jayne; Wang, Dong; Lilley, Catherine J; Urwin, Peter E; Atkinson, Howard J

2012-01-01

Current and future global crop yields depend upon soil quality to which soil organisms make an important contribution. The European Union seeks to protect European soils and their biodiversity for instance by amending its Directive on pesticide usage. This poses a challenge for control of Globodera pallida (a potato cyst nematode) for which both natural resistance and rotational control are inadequate. One approach of high potential is transgenically based resistance. This work demonstrates the potential in the field of a new transgenic trait for control of G. pallida that suppresses root invasion. It also investigates its impact and that of a second transgenic trait on the non-target soil nematode community. We establish that a peptide that disrupts chemoreception of nematodes without a lethal effect provides resistance to G. pallida in both a containment and a field trial when precisely targeted under control of a root tip-specific promoter. In addition we combine DNA barcoding and quantitative PCR to recognise nematode genera from soil samples without microscope-based observation and use the method for nematode faunal analysis. This approach establishes that the peptide and a cysteine proteinase inhibitor that offer distinct bases for transgenic plant resistance to G. pallida do so without impact on the non-target nematode soil community.

The Elusive Search for Reniform Nematode Resistance in Cotton.

PubMed

Khanal, Churamani; McGawley, Edward C; Overstreet, Charles; Stetina, Salliana R

2018-05-01

The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) has emerged as the most important plant-parasitic nematode of cotton in the United States cotton belt. Success in the development of reniform nematode-resistant upland cotton cultivars (Gossypium hirsutum L.) has not been realized despite over three decades of breeding efforts. Research approaches ranging from conventional breeding to triple species hybrids to marker-assisted selection have been employed to introgress reniform nematode resistance from other species of cotton into upland cultivars. Reniform nematode-resistant breeding lines derived from G. longicalyx were developed in 2007. However, these breeding lines displayed stunting symptoms and a hypersensitive response to reniform nematode infection. Subsequent breeding efforts focused on G. barbadense, G. aridum, G. armoreanum, and other species that have a high level of resistance to reniform nematode. Marker-assisted selection has greatly improved screening of reniform nematode-resistant lines. The use of advanced molecular techniques such as CRISPER-Cas9 systems and alternative ways such as delivery of suitable "cry" proteins and specific double-stranded RNA to nematodes will assist in developing resistant cultivars of cotton. In spite of the efforts of cotton breeders and nematologists, successes are limited only to the development of reniform nematode-resistant breeding lines. In this article, we provide an overview of the approaches employed to develop reniform nematode-resistant upland cotton cultivars in the past, progress to date, major obstacles, and some promising future research activity.

Delayed response to ring nematode (Mesocriconema xenoplax) feeding on grape roots linked to vine carbohydrate reserves and nematode feeding pressure

USDA-ARS?s Scientific Manuscript database

The chronic impact of ring nematode (Mesocriconema xenoplax) feeding on grapevine (Vitis vinifera) was studied under controlled conditions. 'Pinot noir' grapevines were exposed to ring nematode or kept nematode-free for three growing seasons, and vines were either grown in full sunlight, 15% of full...

The dual effects of root-cap exudates on nematodes: from quiescence in plant-parasitic nematodes to frenzy in entomopathogenic nematodes.

PubMed

Hiltpold, Ivan; Jaffuel, Geoffrey; Turlings, Ted C J

2015-02-01

To defend themselves against herbivores and pathogens, plants produce numerous secondary metabolites, either constitutively or de novo in response to attacks. An intriguing constitutive example is the exudate produced by certain root-cap cells that can induce a state of reversible quiescence in plant-parasitic nematodes, thereby providing protection against these antagonists. The effect of such root exudates on beneficial entomopathogenic nematodes (EPNs) remains unclear, but could potentially impair their use in pest management programmes. We therefore tested how the exudates secreted by green pea (Pisum sativum) root caps affect four commercial EPN species. The exudates induced reversible quiescence in all EPN species tested. Quiescence levels varied with the green pea cultivars tested. Notably, after storage in root exudate, EPN performance traits were maintained over time, whereas performances of EPNs stored in water rapidly declined. In sharp contrast to high concentrations, lower concentrations of the exudate resulted in a significant increase in EPN activity and infectiousness, but still reduced the activity of two plant-parasitic nematode species. Our study suggests a finely tuned dual bioactivity of the exudate from green pea root caps. Appropriately formulated, it can favour long-term storage of EPNs and boost their infectiousness, while it may also be used to protect plants from plant-parasitic nematodes. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Natural Selection on Individual Variation in Tolerance of Gastrointestinal Nematode Infection

PubMed Central

Hayward, Adam D.; Nussey, Daniel H.; Wilson, Alastair J.; Berenos, Camillo; Pilkington, Jill G.; Watt, Kathryn A.; Pemberton, Josephine M.; Graham, Andrea L.

2014-01-01

Hosts may mitigate the impact of parasites by two broad strategies: resistance, which limits parasite burden, and tolerance, which limits the fitness or health cost of increasing parasite burden. The degree and causes of variation in both resistance and tolerance are expected to influence host–parasite evolutionary and epidemiological dynamics and inform disease management, yet very little empirical work has addressed tolerance in wild vertebrates. Here, we applied random regression models to longitudinal data from an unmanaged population of Soay sheep to estimate individual tolerance, defined as the rate of decline in body weight with increasing burden of highly prevalent gastrointestinal nematode parasites. On average, individuals lost weight as parasite burden increased, but whereas some lost weight slowly as burden increased (exhibiting high tolerance), other individuals lost weight significantly more rapidly (exhibiting low tolerance). We then investigated associations between tolerance and fitness using selection gradients that accounted for selection on correlated traits, including body weight. We found evidence for positive phenotypic selection on tolerance: on average, individuals who lost weight more slowly with increasing parasite burden had higher lifetime breeding success. This variation did not have an additive genetic basis. These results reveal that selection on tolerance operates under natural conditions. They also support theoretical predictions for the erosion of additive genetic variance of traits under strong directional selection and fixation of genes conferring tolerance. Our findings provide the first evidence of selection on individual tolerance of infection in animals and suggest practical applications in animal and human disease management in the face of highly prevalent parasites. PMID:25072883

Rolling Circle Amplification of Complete Nematode Mitochondrial Genomes

PubMed Central

Tang, Sha; Hyman, Bradley C.

2005-01-01

To enable investigation of nematode mitochondrial DNA evolution, methodology has been developed to amplify intact nematode mitochondrial genomes in preparative yields using a rolling circle replication strategy. Successful reactions were generated from whole cell template DNA prepared by alkaline lysis of the rhabditid nematode Caenorhabditis elegans and a mermithid nematode, Thaumamermis cosgrovei. These taxa, representing the two major nematode classes Chromodorea and Enoplea, maintain mitochondrial genomes of 13.8 kb and 20.0 kb, respectively. Efficient amplifications were conducted on template DNA isolated from individual or pooled nematodes that were alive or stored at -80°C. Unexpectedly, these experiments revealed that multiple T. cosgrovei mitochondrial DNA haplotypes are maintained in our local population. Rolling circle amplification products can be used as templates for standard PCR reactions with specific primers that target mitochondrial genes or for direct DNA sequencing. PMID:19262866

Figs, pollinators, and parasites: A longitudinal study of the effects of nematode infection on fig wasp fitness

NASA Astrophysics Data System (ADS)

Van Goor, Justin; Piatscheck, Finn; Houston, Derek D.; Nason, John D.

2018-07-01

Mutualisms are interactions between two species in which the fitnesses of both symbionts benefit from the relationship. Although examples of mutualism are ubiquitous in nature, the ecology, evolution, and stability of mutualism has rarely been studied in the broader, multi-species community context in which they occur. The pollination mutualism between figs and fig wasps provides an excellent model system for investigating interactions between obligate mutualists and antagonists. Compared to the community of non-pollinating fig wasps that develop within fig inflorescences at the expense of fig seeds and pollinators, consequences of interactions between female pollinating wasps and their host-specialist nematode parasites is much less well understood. Here we focus on a tri-partite system comprised of a fig (Ficus petiolaris), pollinating wasp (Pegoscapus sp.), and nematode (Parasitodiplogaster sp.), investigating geographical variation in the incidence of attack and mechanisms through which nematodes may limit the fitness of their wasp hosts at successive life history stages. Observational data reveals that nematodes are ubiquitous across their host range in Baja California, Mexico; that the incidence of nematode infection varies across seasons within- and between locations, and that infected pollinators are sometimes associated with fitness declines through reduced offspring production. We find that moderate levels of infection (1-9 juvenile nematodes per host) are well tolerated by pollinator wasps whereas higher infection levels (≥10 nematodes per host) are correlated with a significant reduction in wasp lifespan and dispersal success. This overexploitation, however, is estimated to occur in only 2.8% of wasps in each generation. The result that nematode infection appears to be largely benign - and the unexpected finding that nematodes frequently infect non-pollinating wasps - highlight gaps in our knowledge of pollinator-Parasitodiplogaster interactions and

Resource utilization and trophic position of nematodes and harpacticoid copepods in and adjacent to Zostera noltii beds

NASA Astrophysics Data System (ADS)

Vafeiadou, A.-M.; Materatski, P.; Adão, H.; De Troch, M.; Moens, T.

2014-07-01

This study examines the resource use and trophic position of nematodes and harpacticoid copepods at the genus/species level in an estuarine food web in Zostera noltii beds and in adjacent bare sediments using the natural abundance of stable carbon and nitrogen isotopes. Microphytobenthos and/or epiphytes are among the main resources of most taxa, but seagrass detritus and sediment particulate organic matter contribute as well to meiobenthos nutrition, which are also available in deeper sediment layers and in unvegetated patches close to seagrass beds. A predominant dependence on chemoautotrophic bacteria was demonstrated for the nematode genus Terschellingia and the copepod family Cletodidae. A predatory feeding mode is illustrated for Paracomesoma and other Comesomatidae, which were previously considered first-level consumers (deposit feeders) according to their buccal morphology. The considerable variation found in both resource use and trophic level among nematode genera from the same feeding type, and even among congeneric nematode species, shows that the interpretation of nematode feeding ecology based purely on mouth morphology should be avoided.

Multifaceted effects of host plants on entomopathogenic nematodes.

PubMed

Hazir, Selcuk; Shapiro-Ilan, David I; Hazir, Canan; Leite, Luis G; Cakmak, Ibrahim; Olson, Dawn

2016-03-01

The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs. Copyright © 2016

Naturally acquired anthrax antibodies in a cheetah (Acinonyx jubatus) in Botswana.

PubMed

Good, Kyle M; Houser, Annmarie; Arntzen, Lorraine; Turnbull, Peter C B

2008-07-01

An outbreak of anthrax in the Jwana Game Reserve in Jwaneng, Botswana, was first observed when three cheetahs (Acinonyx jubatus) died of the disease in November 2004. In the aftermath of this event, banked serum samples collected from 23 wild-caught cheetahs were examined, by the inhibition enzyme-linked immunoassay (ELISA), for antibodies to the protective antigen (PA) of Bacillus anthracis. Of the 23 cheetahs, 16 regularly accessed the reserve. Antibodies to PA were detected in one cheetah collected in May 2004, indicating the disease was occurring well before it was first noticed. This appears to be the first demonstration of naturally acquired anthrax antibodies in cheetahs. The finding of one antibody-positive animal amongst at least 16 potentially exposed individuals is consistent with existing reports that it is uncommon for cheetahs to develop natural immunity to anthrax.

Targeted mutagenesis in a human-parasitic nematode

PubMed Central

Gang, Spencer S.; Castelletto, Michelle L.

2017-01-01

Parasitic nematodes infect over 1 billion people worldwide and cause some of the most common neglected tropical diseases. Despite their prevalence, our understanding of the biology of parasitic nematodes has been limited by the lack of tools for genetic intervention. In particular, it has not yet been possible to generate targeted gene disruptions and mutant phenotypes in any parasitic nematode. Here, we report the development of a method for introducing CRISPR-Cas9-mediated gene disruptions in the human-parasitic threadworm Strongyloides stercoralis. We disrupted the S. stercoralis twitchin gene unc-22, resulting in nematodes with severe motility defects. Ss-unc-22 mutations were resolved by homology-directed repair when a repair template was provided. Omission of a repair template resulted in deletions at the target locus. Ss-unc-22 mutations were heritable; we passed Ss-unc-22 mutants through a host and successfully recovered mutant progeny. Using a similar approach, we also disrupted the unc-22 gene of the rat-parasitic nematode Strongyloides ratti. Our results demonstrate the applicability of CRISPR-Cas9 to parasitic nematodes, and thereby enable future studies of gene function in these medically relevant but previously genetically intractable parasites. PMID:29016680

Naturally acquired antibody responses to recombinant Pfs230 and Pfs48/45 transmission blocking vaccine candidates.

PubMed

Jones, Sophie; Grignard, Lynn; Nebie, Issa; Chilongola, Jaffu; Dodoo, Daniel; Sauerwein, Robert; Theisen, Michael; Roeffen, Will; Singh, Shrawan Kumar; Singh, Rajesh Kumar; Singh, Sanjay; Kyei-Baafour, Eric; Tetteh, Kevin; Drakeley, Chris; Bousema, Teun

2015-07-01

Pfs48/45 and Pfs230 are Plasmodium falciparum sexual stage proteins and promising malaria transmission-blocking vaccine candidates. Antibody responses against these proteins may be naturally acquired and target antigens may be under selective pressure. This has consequences for the future evaluation of vaccine immunogenicity and efficacy in populations naturally exposed to malaria. We determined naturally acquired antibody responses to the recombinant proteins Pfs48/45-10C and Pfs230-230CMB in children from three malaria endemic settings in Ghana, Tanzania and Burkina Faso. We also examined genetic polymorphisms in the P. falciparum gene pfs48/45. Antibody prevalence was 1.1-18.2% for 10C and 6.7-18.9% for 230CMB. In Burkina Faso we observed evidence of an age-dependent acquisition pattern for both 10C (p < 0.001) and 230CMB (p = 0.031). Membrane feeding assays on a separate dataset demonstrated an association between functional transmission reducing activity and antibody prevalence for both 10C (p = 0.017) and 230CMB (p = 0.049). 17 single nucleotide polymorphisms were found in pfs48/45 (from 126 samples), with 5 non-synonymous SNPs in the Pfs48/45 10C region. We conclude there are naturally acquired antibody responses to both vaccine candidates which have functional relevance by reducing the transmissibility of infected individuals. We identified genetic polymorphisms, in pfs48/45 which exhibited geographical specificity. Copyright © 2015 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Anthelmintic resistance in gastrointestinal nematodes of beef cattle in the state of Rio Grande do Sul, Brazil

PubMed Central

Ramos, Fernanda; Portella, Luiza Pires; Rodrigues, Fernando de Souza; Reginato, Caroline Zamperete; Pötter, Luciana; Cezar, Alfredo Skrebsky; Sangioni, Luís Antônio; Vogel, Fernanda Silveira Flores

2016-01-01

Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70–100 calves or more of both genders with ≥200 eggs per gram of feces (EPG) (sensitivity of 50 EPG). These calves were distributed into 10 groups (of 7–10 animals) per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7–10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different chemical groups

Anthelmintic resistance in gastrointestinal nematodes of beef cattle in the state of Rio Grande do Sul, Brazil.

PubMed

Ramos, Fernanda; Portella, Luiza Pires; Rodrigues, Fernando de Souza; Reginato, Caroline Zamperete; Pötter, Luciana; Cezar, Alfredo Skrebsky; Sangioni, Luís Antônio; Vogel, Fernanda Silveira Flores

2016-04-01

Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70-100 calves or more of both genders with ≥ 200 eggs per gram of feces (EPG) (sensitivity of 50 EPG). These calves were distributed into 10 groups (of 7-10 animals) per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7-10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different chemical groups were effective

Opportunity to use native nematodes for pest control

USDA-ARS?s Scientific Manuscript database

We have surveyed wild cranberry bogs in WI and found three isolates of native nematodes. We have been testing these nematodes as potential biological control agents in for cranberry insect pests including sparganothis fruitworm and flea beetle. The nematodes seem to be effective at finding and killi...

Basic and applied research: Entomopathogenic nematodes

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema kill arthropods with the aid of their bacterial symbionts. These nematodes are potent microbial control agents that have been widely commercialized for control of economically important insect pests. Biocontrol efficacy relies...

Interspecific nematode signals regulate dispersal behavior

USDA-ARS?s Scientific Manuscript database

Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective ...

Nematode infection in liver of the fish Gymnotus inaequilabiatus (Gymnotiformes: Gymnotidae) from the Pantanal Region in Brazil: pathobiology and inflammatory response.

PubMed

Sayyaf Dezfuli, Bahram; Fernandes, Carlos E; Galindo, Gizela M; Castaldelli, Giuseppe; Manera, Maurizio; DePasquale, Joseph A; Lorenzoni, Massimo; Bertin, Sara; Giari, Luisa

2016-08-30

A survey on endoparasitic helminths from freshwater fishes in the Pantanal Region (Mato Grosso do Sul, Brazil) revealed the occurrence of third-larval stage of the nematode Brevimulticaecum sp. (Heterocheilidae) in most organs of Gymnotus inaequilabiatus (Gymnotidae) also known by the local name tuvira. The aim of the present study was to examine Brevimulticaecum sp.-infected tuvira liver at the ultrastructural level and clarify the nature of granulomas and the cellular elements involved in the immune response to nematode larvae. Thirty-eight adult specimens of tuvira from Porto Morrinho, were acquired in January and March 2016. Infected and uninfected liver tissues were fixed and prepared for histological and ultrastructure investigations. The prevalence of infection of tuvira liver by the nematode larvae was 95 %, with an intensity of infection ranging from 4 to 343 larvae (mean ± SD: 55.31 ± 73.94 larvae per liver). In livers with high numbers of nematode larvae, almost entire hepatic tissue was occupied by the parasites. Hepatocytes showed slight to mild degenerative changes and accumulation of pigments. Parasite larvae were surrounded by round to oval granulomas, the result of focal host tissue response to the infection. Each granuloma was typically formed by three concentric layers: an outer layer of fibrous connective tissue with thin elongated fibroblasts; a middle layer of mast cells entrapped in a thin fibroblast-connective mesh; and an inner layer of densely packed epithelioid cells, displaying numerous desmosomes between each other. Numerous macrophage aggregates occurred in the granulomas and in the parenchyma. Our results in tuvira showed that the larvae were efficiently sequestered within the granulomas, most of the inflammatory components were confined within the thickness of the granuloma, and the parenchyma was relatively free of immune cells and without fibrosis. Presumably this focal encapsulation of the parasites permits uninfected

Multipartite Symbioses Among Fungi, Mites, Nematodes, and the Spruce Beetle, Dendroctonus rufipennis.

Treesearch

Yasmin Cardoza; John Moser; Kier Klepzizg; Raffa Kenneth

2008-01-01

The spruce beetle, Dendroctonus rufipennis, is an eruptive forest pest of signifcant economic and ecological importance. D. rufipennis has symbiotic associations with a number of microorganisms, especially the ophiostomatoid fungus Leptographium abietinum. The nature of this interaction is only partially understood. Additionally, mite and nematode associates can...

Cryopreservation of roe deer abomasal nematodes for morphological identification.

PubMed

Beraldo, Paola; Pascotto, Ernesto

2014-02-01

Conventional methods to preserve adult nematodes for taxonomic purposes involve the use of fixative or clearing solutions (alcohol, formaldehyde, AFA and lactophenol), which cause morphological alterations and are toxic. The aim of this study is to propose an alternative method based on glycerol-cryopreservation of nematodes for their subsequent identification. Adults of trichostrongylid nematodes from the abomasum of roe deer (Capreolus capreolus Linnaeus) were glycerol-cryopreserved and compared with those fixed in formaldehyde, fresh and frozen without cryoprotectans. Morphology, transparency and elasticity of the anterior and posterior portion of male nematodes were compared, especially the caudal cuticular bursa and genital accessories. The method presented is quick and easy to use, and the quality of nematode specimens is better than that of nematodes fixed by previously used fixatives. Moreover, glycerol cryopreserved nematodes can be stored for a long time at -20 degrees C in perfect condition and they could be suitable for further analyses, such as histological or ultrastructural examinations.

SlWRKY45, nematode-responsive tomato WRKY gene, enhances susceptibility to the root knot nematode; M. javanica infection.

PubMed

Chinnapandi, Bharathiraja; Bucki, Patricia; Braun Miyara, Sigal

2017-12-02

The fluctuation of tomato's WRKY defense regulators during infection by the root knot nematode Meloidogyne javanica was analyzed: and the spatial and temporal expression of SlWRKY45 was studied in depth with regard to its response to nematode infection, phytohormones, and wounding. Expression of WRKY45 increased substantially within 5 d upon infection and continued through feeding-site development and gall maturation. Histological analysis of nematode feeding sites indicated that WRKY45 was highly expressed within the feeding cells and associated vascular parenchyma cells. Responses of SlWRKY45 promoters to several phytohormones showed that WRKY45 was highly induced by specific phytohormones, including cytokinin, auxin, and the defense-signaling molecule salicylic acid (SA), but not by the jasmonates. Overexpressing tomato lines were generated, and infection tests showed that, significantly, roots over-expressing SlWRKY45 contained substantially increased number of females, indicating that WRKY45 overexpression supported faster nematode development. qRT-PCR tests have shown roots overexpressing WRKY45 suppressed the jasmonic acid and salicylic acid marker genes, proteinase inhibitor (PI), and pathogenesis related protein (PR1), respectively, and also the cytokinin response factors CRF1 and CRF6. Overall, this study indicated SlWRKY45 to be a potential transcription factor whose manipulation by the invading nematode might be critical for coordination of hormone signals supporting favorable condition for nematode development in root tissue.

Pan-phylum Comparison of Nematode Metabolic Potential

PubMed Central

Tyagi, Rahul; Rosa, Bruce A.; Lewis, Warren G.; Mitreva, Makedonka

2015-01-01

Nematodes are among the most important causative pathogens of neglected tropical diseases. The increased availability of genomic and transcriptomic data for many understudied nematode species provides a great opportunity to investigate different aspects of their biology. Increasingly, metabolic potential of pathogens is recognized as a critical determinant governing their development, growth and pathogenicity. Comparing metabolic potential among species with distinct trophic ecologies can provide insights on overall biology or molecular adaptations. Furthermore, ascertaining gene expression at pathway level can help in understanding metabolic dynamics over development. Comparison of biochemical pathways (or subpathways, i.e. pathway modules) among related species can also retrospectively indicate potential mistakes in gene-calling and functional annotation. We show with numerous illustrative case studies that comparisons at the level of pathway modules have the potential to uncover biological insights while remaining computationally tractable. Here, we reconstruct and compare metabolic modules found in the deduced proteomes of 13 nematodes and 10 non-nematode species (including hosts of the parasitic nematode species). We observed that the metabolic potential is, in general, concomitant with phylogenetic and/or ecological similarity. Varied metabolic strategies are required among the nematodes, with only 8 out of 51 pathway modules being completely conserved. Enzyme comparison based on topology of metabolic modules uncovered diversification between parasite and host that can potentially guide therapeutic intervention. Gene expression data from 4 nematode species were used to study metabolic dynamics over their life cycles. We report unexpected differential metabolism between immature and mature microfilariae of the human filarial parasite Brugia malayi. A set of genes potentially important for parasitism is also reported, based on an analysis of gene expression in

Nitrogen Addition Regulates Soil Nematode Community Composition through Ammonium Suppression

PubMed Central

Wei, Cunzheng; Zheng, Huifen; Li, Qi; Lü, Xiaotao; Yu, Qiang; Zhang, Haiyang; Chen, Quansheng; He, Nianpeng; Kardol, Paul; Liang, Wenju; Han, Xingguo

2012-01-01

Nitrogen (N) enrichment resulting from anthropogenic activities has greatly changed the composition and functioning of soil communities. Nematodes are one of the most abundant and diverse groups of soil organisms, and they occupy key trophic positions in the soil detritus food web. Nematodes have therefore been proposed as useful indicators for shifts in soil ecosystem functioning under N enrichment. Here, we monitored temporal dynamics of the soil nematode community using a multi-level N addition experiment in an Inner Mongolia grassland. Measurements were made three years after the start of the experiment. We used structural equation modeling (SEM) to explore the mechanisms regulating nematode responses to N enrichment. Across the N enrichment gradient, significant reductions in total nematode abundance, diversity (H' and taxonomic richness), maturity index (MI), and the abundance of root herbivores, fungivores and omnivores-predators were found in August. Root herbivores recovered in September, contributing to the temporal variation of total nematode abundance across the N gradient. Bacterivores showed a hump-shaped relationship with N addition rate, both in August and September. Ammonium concentration was negatively correlated with the abundance of total and herbivorous nematodes in August, but not in September. Ammonium suppression explained 61% of the variation in nematode richness and 43% of the variation in nematode trophic group composition. Ammonium toxicity may occur when herbivorous nematodes feed on root fluid, providing a possible explanation for the negative relationship between herbivorous nematodes and ammonium concentration in August. We found a significantly positive relationship between fungivores and fungal phospholipid fatty acids (PLFA), suggesting bottom-up control of fungivores. No such relationship was found between bacterivorous nematodes and bacterial PLFA. Our findings contribute to the understanding of effects of N enrichment in

Identification, Validation and Utilization of Novel Nematode-Responsive Root-Specific Promoters in Arabidopsis for Inducing Host-Delivered RNAi Mediated Root-Knot Nematode Resistance

PubMed Central

Kakrana, Atul; Kumar, Anil; Satheesh, Viswanathan; Abdin, M. Z.; Subramaniam, Kuppuswamy; Bhattacharya, R. C.; Srinivasan, Ramamurthy; Sirohi, Anil; Jain, Pradeep K.

2017-01-01

The root-knot nematode (RKN), Meloidogyne incognita, is an obligate, sedentary endoparasite that infects a large number of crops and severely affects productivity. The commonly used nematode control strategies have their own limitations. Of late, RNA interference (RNAi) has become a popular approach for the development of nematode resistance in plants. Transgenic crops capable of expressing dsRNAs, specifically in roots for disrupting the parasitic process, offer an effective and efficient means of producing resistant crops. We identified nematode-responsive and root-specific (NRRS) promoters by using microarray data from the public domain and known conserved cis-elements. A set of 51 NRRS genes was identified which was narrowed down further on the basis of presence of cis-elements combined with minimal expression in the absence of nematode infection. The comparative analysis of promoters from the enriched NRRS set, along with earlier reported nematode-responsive genes, led to the identification of specific cis-elements. The promoters of two candidate genes were used to generate transgenic plants harboring promoter GUS constructs and tested in planta against nematodes. Both promoters showed preferential expression upon nematode infection, exclusively in the root in one and galls in the other. One of these NRRS promoters was used to drive the expression of splicing factor, a nematode-specific gene, for generating host-delivered RNAi-mediated nematode-resistant plants. Transgenic lines expressing dsRNA of splicing factor under the NRRS promoter exhibited upto a 32% reduction in number of galls compared to control plants. PMID:29312363

Endemic Oscheius Nematodes of Hawai'i

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes (EPNs) parasitize insects utilizing mutualistic bacteria to kill the host, allowing the nematode to feed and reproduce within the insect cadaver. Consequently EPNs are highly sought after for their biological control potential. A survey for EPNs was conducted on O’ahu and...

Quantifying the Contribution of Entire Free-Living Nematode Communities to Carbon Mineralization under Contrasting C and N Availability

PubMed Central

Gebremikael, Mesfin Tsegaye; Steel, Hanne; Bert, Wim; Maenhout, Peter; Sleutel, Steven; De Neve, Stefaan

2015-01-01

To understand the roles of nematodes in organic matter (OM) decomposition, experimental setups should include the entire nematode community, the native soil microflora, and their food sources. Yet, published studies are often based on either simplified experimental setups, using only a few selected species of nematode and their respective prey, despite the multitude of species present in natural soil, or on indirect estimation of the mineralization process using O2 consumption and the fresh weight of nematodes. We set up a six-month incubation experiment to quantify the contribution of the entire free living nematode community to carbon (C) mineralization under realistic conditions. The following treatments were compared with and without grass-clover amendment: defaunated soil reinoculated with the entire free living nematode communities (+Nem) and defaunated soil that was not reinoculated (-Nem). We also included untreated fresh soil as a control (CTR). Nematode abundances and diversity in +Nem was comparable to the CTR showing the success of the reinoculation. No significant differences in C mineralization were found between +Nem and -Nem treatments of the amended and unamended samples at the end of incubation. Other related parameters such as microbial biomass C and enzymatic activities did not show significant differences between +Nem and -Nem treatments in both amended and unamended samples. These findings show that the collective contribution of the entire nematode community to C mineralization is small. Previous reports in literature based on simplified experimental setups and indirect estimations are contrasting with the findings of the current study and further investigations are needed to elucidate the extent and the mechanisms of nematode involvement in C mineralization. PMID:26393517

Biological Control Potential of Neoaplectanid Nematodes

PubMed Central

Gaugler, Randy

1981-01-01

The neoaplectanids are among the most studied of all entomogenous nematodes. Because these nematodes kill their insect hosts, they are regarded as having excellent potential as biological control agents. While the host specificity of most entontogenous nematodes tends to limit their potential usefulness, the broad host range and high virulence of neoaplectanids make them attractive candidates for industrial development. Also, recent development of economical mass rearing procedures appears to make production on a commercial basis feasible. Infective stages may be stored for years trader various laboratory conditions. Although entomogenous nematodes, as parasites, are exempt from govermnent registration requirements, the mutualistic association of neoaplectanid nematodes with a bacterium will likely necessitate a detailed safety evaluation. Studies conducted to date indicate a lack of pathogenicity to mammals. Field trial success has been limited by the intolerance of infective stages to mffavorable environmental conditions, particularly low moisture. Applications against pests on exposed plant foliage have been especially disappointing. More encouraging anti consistent results have been obtained in more favorable environments, including soil and aquatic habitats, but the most promising treatment sites ntay be cryptic habitats where infective stages are shehered from environmental extremes. Cryptic habitats also exploit the ability of neoaplectanids to actively seek out hosts in recessed places where conventional insecticide applications are intpractical. PMID:19300757

Checklist of nematode parasites of amphibians from Argentina.

PubMed

González, Cynthya Elizabeth; Inés, Hamann Monika

2015-07-01

This review includes information about 47 taxa of nematode parasites reported from 34 species of Argentinean amphibians, all belonging to order Anura (33 native species and 1 introduced species). Thirty four nematode species have been reported as adults and 13 species were reported as larvae (10 taxa) or juveniles (3 taxa). Two species, Cosmocerca parva and C. podicipinus (Cosmocercidae), collected as adults, are the most commonly occurring adult nematodes in Argentinean amphibians; each of them parasitize 14 amphibian species. The bufonid Rhinella schneideri and the leptodactylid Leptodactylus bufonius present the highest species richness of parasitic nematodes (9 species); followed by Rhinella fernandezae, R. arenarum and Leptodactylus chaquensis, each of which is parasitized by 8 nematode species. Mean species richenss was highest for the family Bufonidae (4.5±3.4; range: 1-9); followed by the Leptodactylidae (3.5±2.8; range: 1-9). Data on hosts, geographical distribution, site of infection, location of deposited materials, and information about life cycles are provided. This is the first compilation of information on nematode parasites of amphibians in Argentina.

Large-scale distribution patterns of mangrove nematodes: A global meta-analysis.

PubMed

Brustolin, Marco C; Nagelkerken, Ivan; Fonseca, Gustavo

2018-05-01

Mangroves harbor diverse invertebrate communities, suggesting that macroecological distribution patterns of habitat-forming foundation species drive the associated faunal distribution. Whether these are driven by mangrove biogeography is still ambiguous. For small-bodied taxa, local factors and landscape metrics might be as important as macroecology. We performed a meta-analysis to address the following questions: (1) can richness of mangrove trees explain macroecological patterns of nematode richness? and (2) do local landscape attributes have equal or higher importance than biogeography in structuring nematode richness? Mangrove areas of Caribbean-Southwest Atlantic, Western Indian, Central Indo-Pacific, and Southwest Pacific biogeographic regions. We used random-effects meta-analyses based on natural logarithm of the response ratio (lnRR) to assess the importance of macroecology (i.e., biogeographic regions, latitude, longitude), local factors (i.e., aboveground mangrove biomass and tree richness), and landscape metrics (forest area and shape) in structuring nematode richness from 34 mangroves sites around the world. Latitude, mangrove forest area, and forest shape index explained 19% of the heterogeneity across studies. Richness was higher at low latitudes, closer to the equator. At local scales, richness increased slightly with landscape complexity and decreased with forest shape index. Our results contrast with biogeographic diversity patterns of mangrove-associated taxa. Global-scale nematode diversity may have evolved independently of mangrove tree richness, and diversity of small-bodied metazoans is probably more closely driven by latitude and associated climates, rather than local, landscape, or global biogeographic patterns.

Betaine acts on a ligand-gated ion channel in the nervous system of the nematode C. elegans

PubMed Central

Peden, Aude S.; Mac, Patrick; Fei, You-Jun; Castro, Cecilia; Jiang, Guoliang; Murfitt, Kenneth J.; Miska, Eric A.; Griffin, Julian L.; Ganapathy, Vadivel; Jorgensen, Erik M.

2014-01-01

Prior to the advent of synthetic nematocides, natural products such as seaweed were used to control nematode infestations. The nematocidal agent in seaweed is betaine, an amino acid that functions as an osmolyte and methyl donor. However, the molecular mechanisms of betaine toxicity are unknown. Here, we identify the betaine transporter SNF-3 and a betaine receptor ACR-23 in the nematode C. elegans. Mutating snf-3 in a sensitized background causes the animals to be hypercontracted and paralyzed, presumably because of excess extracellular betaine. These behavioral defects are suppressed by mutations in acr-23, which encodes a ligand-gated cation channel of the cys-loop family. ACR-23 is activated by betaine and functions in the mechanosensory neurons to maintain basal levels of locomotion. However, overactivation of the receptor by excess betaine or by the allosteric modulator monepantel causes hypercontraction and death of the nematode. Thus, monepantel targets a betaine signaling pathway in nematodes. PMID:24212673

First case of a naturally acquired human infection with Plasmodium cynomolgi

PubMed Central

2014-01-01

Since 1960, a total of seven species of monkey malaria have been reported as transmissible to man by mosquito bite: Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium eylesi, Plasmodium knowlesi, Plasmodium inui, Plasmodium schwetzi and Plasmodium simium. With the exception of P. knowlesi, none of the other species has been found to infect humans in nature. In this report, it is described the first known case of a naturally acquired P. cynomolgi malaria in humans. The patient was a 39-year-old woman from a malaria-free area with no previous history of malaria or travel to endemic areas. Initially, malaria was diagnosed and identified as Plasmodium malariae/P. knowlesi by microscopy in the Terengganu State Health Department. Thick and thin blood films stained with 10% Giemsa were performed for microscopy examination. Molecular species identification was performed at the Institute for Medical Research (IMR, Malaysia) and in the Malaria & Emerging Parasitic Diseases Laboratory (MAPELAB, Spain) using different nested PCR methods. Microscopic re-examination in the IMR showed characteristics of Plasmodium vivax and was confirmed by a nested PCR assay developed by Snounou et al. Instead, a different PCR assay plus sequencing performed at the MAPELAB confirmed that the patient was infected with P. cynomolgi and not with P. vivax. This is the first report of human P. cynomolgi infection acquired in a natural way, but there might be more undiagnosed or misdiagnosed cases, since P. cynomolgi is morphologically indistinguishable from P. vivax, and one of the most used PCR methods for malaria infection detection may identify a P. cynomolgi infection as P. vivax. Simian Plasmodium species may routinely infect humans in Southeast Asia. New diagnostic methods are necessary to distinguish between the human and monkey malaria species. Further epidemiological studies, incriminating also the mosquito vector(s), must be performed to know the relevance of cynomolgi malaria and its

First case of a naturally acquired human infection with Plasmodium cynomolgi.

PubMed

Ta, Thuy H; Hisam, Shamilah; Lanza, Marta; Jiram, Adela I; Ismail, NorParina; Rubio, José M

2014-02-24

Since 1960, a total of seven species of monkey malaria have been reported as transmissible to man by mosquito bite: Plasmodium cynomolgi, Plasmodium brasilianum, Plasmodium eylesi, Plasmodium knowlesi, Plasmodium inui, Plasmodium schwetzi and Plasmodium simium. With the exception of P. knowlesi, none of the other species has been found to infect humans in nature. In this report, it is described the first known case of a naturally acquired P. cynomolgi malaria in humans.The patient was a 39-year-old woman from a malaria-free area with no previous history of malaria or travel to endemic areas. Initially, malaria was diagnosed and identified as Plasmodium malariae/P. knowlesi by microscopy in the Terengganu State Health Department. Thick and thin blood films stained with 10% Giemsa were performed for microscopy examination. Molecular species identification was performed at the Institute for Medical Research (IMR, Malaysia) and in the Malaria & Emerging Parasitic Diseases Laboratory (MAPELAB, Spain) using different nested PCR methods.Microscopic re-examination in the IMR showed characteristics of Plasmodium vivax and was confirmed by a nested PCR assay developed by Snounou et al. Instead, a different PCR assay plus sequencing performed at the MAPELAB confirmed that the patient was infected with P. cynomolgi and not with P. vivax.This is the first report of human P. cynomolgi infection acquired in a natural way, but there might be more undiagnosed or misdiagnosed cases, since P. cynomolgi is morphologically indistinguishable from P. vivax, and one of the most used PCR methods for malaria infection detection may identify a P. cynomolgi infection as P. vivax.Simian Plasmodium species may routinely infect humans in Southeast Asia. New diagnostic methods are necessary to distinguish between the human and monkey malaria species. Further epidemiological studies, incriminating also the mosquito vector(s), must be performed to know the relevance of cynomolgi malaria and its

Free-Living Nematodes in the Freshwater Food Web: A Review

PubMed Central

Majdi, Nabil; Traunspurger, Walter

2015-01-01

Free-living nematodes are well-recognized as an abundant and ubiquitous component of benthic communities in inland waters. Compelling evidence from soil and marine ecosystems has highlighted the importance of nematodes as trophic intermediaries between microbial production and higher trophic levels. However, the paucity of empirical evidence of their role in freshwater ecosystems has hampered their inclusion in our understanding of freshwater food web functioning. This literature survey provides an overview of research efforts in the field of freshwater nematode ecology and of the complex trophic interactions between free-living nematodes and microbes, other meiofauna, macro-invertebrates, and fishes. Based on an analysis of the relevant literature and an appreciation of the potential of emerging approaches for the evaluation of nematode trophic ecology, we point out research gaps and recommend relevant directions for further research. The latter include (i) interactions of nematodes with protozoans and fungi; (ii) nonconsumptive effects of nematodes on microbial activity and the effects of nematodes on associated key ecosystem processes (decomposition, primary production); and (iii) the feeding selectivity and intraspecific feeding variability of nematodes and their potential impacts on the structure of benthic communities. PMID:25861114

Effect of dietary insoluble fiber on control of glycemia in dogs with naturally acquired diabetes mellitus.

PubMed

Nelson, R W; Duesberg, C A; Ford, S L; Feldman, E C; Davenport, D J; Kiernan, C; Neal, L

1998-02-01

To evaluate the effect of a high insoluble-fiber (HF) diet containing 12% cellulose in dry matter and a low insoluble-fiber (LF) diet on control of glycemia in dogs with naturally acquired insulin-dependent diabetes mellitus. Prospective randomized crossover controlled trial. 11 dogs with naturally acquired diabetes mellitus. Dogs were fed HF and LF diets for 8 months each in 1 of 2 randomly assigned diet sequences. Caloric intake and insulin treatment were adjusted as needed to maintain stable body weight and control of glycemia, respectively. After a 2-month adaptation period, control of glycemia was evaluated every 6 weeks for 6 months. Variables assessed included serum glucose concentration measured during the preprandial state, blood glycosylated hemoglobin concentration, serum glucose concentration measured every 2 hours for 24 hours beginning at the time of the morning insulin injection, 24-hour mean serum glucose concentration, mean serum glucose concentration fluctuation from the 24-hour mean serum glucose concentration, and 24-hour urinary excretion of glucose. Significant differences in mean daily caloric intake, body weight, or daily insulin dosage among dogs fed HF and LF diets were not found. Mean preprandial serum glucose concentration, most postprandial serum glucose concentrations, 24-hour mean serum glucose concentration, and 24-hour urinary excretion of glucose were significantly lower in dogs fed the HF diet, compared with the LF diet. Results of this study support feeding of commercially available insoluble fiber diets to dogs with naturally acquired diabetes mellitus.

Mind the gaps in research on the control of gastrointestinal nematodes of farmed ruminants and pigs.

PubMed

Charlier, J; Thamsborg, S M; Bartley, D J; Skuce, P J; Kenyon, F; Geurden, T; Hoste, H; Williams, A R; Sotiraki, S; Höglund, J; Chartier, C; Geldhof, P; van Dijk, J; Rinaldi, L; Morgan, E R; von Samson-Himmelstjerna, G; Vercruysse, J; Claerebout, E

2018-05-01

Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. In this synthetic review, we identify key research priorities for GI nematode control in farmed ruminants and pigs, to support the development of roadmaps and strategic research agendas by governments, industry and policymakers. These priorities were derived from the DISCONTOOLS gap analysis for nematodes and follow-up discussions within the recently formed Livestock Helminth Research Alliance (LiHRA). In the face of ongoing spread of anthelmintic resistance (AR), we are increasingly faced with a failure of existing control methods against GI nematodes. Effective vaccines against GI nematodes are generally not available, and anthelmintic treatment will therefore remain a cornerstone for their effective control. At the same time, consumers and producers are increasingly concerned with environmental issues associated with chemical parasite control. To address current challenges in GI nematode control, it is crucial to deepen our insights into diverse aspects of epidemiology, AR, host immune mechanisms and the socio-psychological aspects of nematode control. This will enhance the development, and subsequent uptake, of the new diagnostics, vaccines, pharma-/nutraceuticals, control methods and decision support tools required to respond to the spread of AR and the shifting epidemiology of GI nematodes in response to climatic, land-use and farm husbandry changes. More emphasis needs to be placed on the upfront evaluation of the economic value of these innovations as well as the socio-psychological aspects to prioritize research and facilitate uptake of innovations in practice. Finally, targeted regulatory guidance is needed to create an innovation-supportive environment for industries and to accelerate the access to market of new control tools. © 2017 Blackwell Verlag GmbH.

Venereal worms: sexually transmitted nematodes in the decorated cricket.

PubMed

Luong, L T; Platzer, E G; Zuk, M; Giblin-Davis, R M

2000-06-01

The nematode, Mehdinema alii, occurs in the alimentary canal of the decorated cricket Gryllodes sigillatus. Adult nematodes occur primarily in the hindgut of mature male crickets, whereas juvenile nematodes are found in the genital chambers of mature male and female crickets. Here, we present experimental evidence for the venereal transmission of M. alii in G. sigillatus. Infectivity experiments were conducted to test for transmission via oral-fecal contamination, same-sex contact, and copulation. The infective dauers of the nematode are transferred from male to female crickets during copulation. Adult female crickets harboring infective dauers subsequently transfer the nematode to their next mates. Thus, M. alii is transmitted sexually during copulation.

Genome Evolution of Plant-Parasitic Nematodes.

PubMed

Kikuchi, Taisei; Eves-van den Akker, Sebastian; Jones, John T

2017-08-04

Plant parasitism has evolved independently on at least four separate occasions in the phylum Nematoda. The application of next-generation sequencing (NGS) to plant-parasitic nematodes has allowed a wide range of genome- or transcriptome-level comparisons, and these have identified genome adaptations that enable parasitism of plants. Current genome data suggest that horizontal gene transfer, gene family expansions, evolution of new genes that mediate interactions with the host, and parasitism-specific gene regulation are important adaptations that allow nematodes to parasitize plants. Sequencing of a larger number of nematode genomes, including plant parasites that show different modes of parasitism or that have evolved in currently unsampled clades, and using free-living taxa as comparators would allow more detailed analysis and a better understanding of the organization of key genes within the genomes. This would facilitate a more complete understanding of the way in which parasitism has shaped the genomes of plant-parasitic nematodes.

The Natural Biotic Environment of Caenorhabditis elegans.

PubMed

Schulenburg, Hinrich; Félix, Marie-Anne

2017-05-01

Organisms evolve in response to their natural environment. Consideration of natural ecological parameters are thus of key importance for our understanding of an organism's biology. Curiously, the natural ecology of the model species Caenorhabditis elegans has long been neglected, even though this nematode has become one of the most intensively studied models in biological research. This lack of interest changed ∼10 yr ago. Since then, an increasing number of studies have focused on the nematode's natural ecology. Yet many unknowns still remain. Here, we provide an overview of the currently available information on the natural environment of C. elegans We focus on the biotic environment, which is usually less predictable and thus can create high selective constraints that are likely to have had a strong impact on C. elegans evolution. This nematode is particularly abundant in microbe-rich environments, especially rotting plant matter such as decomposing fruits and stems. In this environment, it is part of a complex interaction network, which is particularly shaped by a species-rich microbial community. These microbes can be food, part of a beneficial gut microbiome, parasites and pathogens, and possibly competitors. C. elegans is additionally confronted with predators; it interacts with vector organisms that facilitate dispersal to new habitats, and also with competitors for similar food environments, including competitors from congeneric and also the same species. Full appreciation of this nematode's biology warrants further exploration of its natural environment and subsequent integration of this information into the well-established laboratory-based research approaches. Copyright © 2017 by the Genetics Society of America.

The FMRFamide-Like Peptide Family in Nematodes

PubMed Central

Peymen, Katleen; Watteyne, Jan; Frooninckx, Lotte; Schoofs, Liliane; Beets, Isabel

2014-01-01

In the three decades since the FMRFamide peptide was isolated from the mollusk Macrocallista nimbosa, structurally similar peptides sharing a C-terminal RFamide motif have been identified across the animal kingdom. FMRFamide-like peptides (FLPs) represent the largest known family of neuropeptides in invertebrates. In the phylum Nematoda, at least 32 flp-genes are classified, making the FLP system of nematodes unusually complex. The diversity of the nematode FLP complement is most extensively mapped in Caenorhabditis elegans, where over 70 FLPs have been predicted. FLPs have shown to be expressed in the majority of the 302 C. elegans neurons including interneurons, sensory neurons, and motor neurons. The vast expression of FLPs is reflected in the broad functional repertoire of nematode FLP signaling, including neuroendocrine and neuromodulatory effects on locomotory activity, reproduction, feeding, and behavior. In contrast to the many identified nematode FLPs, only few peptides have been assigned a receptor and there is the need to clarify the pathway components and working mechanisms of the FLP signaling network. Here, we review the diversity, distribution, and functions of FLPs in nematodes. PMID:24982652

Linear distribution of nematodes in the gastrointestinal tract of tracer lambs.

PubMed

Makovcová, Katerina; Langrová, Iva; Vadlejch, Jaroslav; Jankovská, Ivana; Lytvynets, Andriy; Borkovcová, Marie

2008-12-01

Forty-eight tracer lambs were killed in 2004-2007. The abomasum, duodenum, small intestine (jejunum and ileum), colon and caecum were collected and processed for parasites enumeration and identification-mucosal scrapings of both abomasums and intestines were digested. Out of 48 gastrointestinal tracts examined, all were found to be positive for nematode infection. Seventeen species of gastrointestinal nematodes were recovered: Bunostomum trigonocephalum, Cooperia curticei, Haemonchus contortus, Chabertia ovina, Nematodirus battus, Nematodirus filicollis, Oesophagostomum venulosum, Teladorsagia circumcincta, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus vitrinus, Strongyloides papillosus, Trichuris ovis, Trichuris globulosa, Trichuris skrjabini and Skrjabinema ovis. All species were searched for in the entire gastrointestinal tract. Six species of nematodes were recovered from abnormal sites, naturally in small numbers of lambs as well as in small amounts: Nematodirus battus in the abomasums (6.67% of lambs), N. filicollis in the caecum and in the colon (%4 and 8%, respectively), T. axei in the colon (9.52%), T. colubriformis in the colon (13.89%), T. vitrinus in the caecum (16.67%), in the colon (20.00%) and in the abomasum (3.33%). T. ovis was found in one case in the small intestine.

Sex-specific mating pheromones in the nematode Panagrellus redivivus.

PubMed

Choe, Andrea; Chuman, Tatsuji; von Reuss, Stephan H; Dossey, Aaron T; Yim, Joshua J; Ajredini, Ramadan; Kolawa, Adam A; Kaplan, Fatma; Alborn, Hans T; Teal, Peter E A; Schroeder, Frank C; Sternberg, Paul W; Edison, Arthur S

2012-12-18

Nematodes use an extensive chemical language based on glycosides of the dideoxysugar ascarylose for developmental regulation (dauer formation), male sex attraction, aggregation, and dispersal. However, no examples of a female- or hermaphrodite-specific sex attractant have been identified to date. In this study, we investigated the pheromone system of the gonochoristic sour paste nematode Panagrellus redivivus, which produces sex-specific attractants of the opposite sex. Activity-guided fractionation of the P. redivivus exometabolome revealed that males are strongly attracted to ascr#1 (also known as daumone), an ascaroside previously identified from Caenorhabditis elegans hermaphrodites. Female P. redivivus are repelled by high concentrations of ascr#1 but are specifically attracted to a previously unknown ascaroside that we named dhas#18, a dihydroxy derivative of the known ascr#18 and an ascaroside that features extensive functionalization of the lipid-derived side chain. Targeted profiling of the P. redivivus exometabolome revealed several additional ascarosides that did not induce strong chemotaxis. We show that P. redivivus females, but not males, produce the male-attracting ascr#1, whereas males, but not females, produce the female-attracting dhas#18. These results show that ascaroside biosynthesis in P. redivivus is highly sex-specific. Furthermore, the extensive side chain functionalization in dhas#18, which is reminiscent of polyketide-derived natural products, indicates unanticipated biosynthetic capabilities in nematodes.

Biological Effect of Leaf Aqueous Extract of Caesalpinia pyramidalis in Goats Naturally Infected with Gastrointestinal Nematodes

PubMed Central

Borges-dos-Santos, Roberto Robson; López, Jorge A.; Santos, Luciano C.; Zacharias, Farouk; David, Jorge Maurício; David, Juceni Pereira; Lima, Fernanda Washington de Mendonça

2012-01-01

Forty-eight goats naturally infected with gastrointestinal nematodes were randomly divided into four groups (n = 12): negative control (G1) (untreated), positive control (G2) (treated with doramectin, 1 mL/50 Kg b.w.), and G3 and G4 treated with 2.5 and 5 mg/Kg b.w. of a leaf aqueous extract of Caesalpinia pyramidalis (CP). Fecal and blood samples were regularly collected for the evaluation of fecal egg count (FEC), hematological and immunological parameters to assess the anthelmintic activity. In treated animals with CP, there was noted a significant reduction of 54.6 and 71.2% in the mean FEC (P < 0.05). An increase in IgA levels was observed in G3 and G4 (P < 0.05), during the experimental period, suggesting that it was stimulated by the extract administration. In conclusion, the results showed that CP provoked a protective response in infected animals treated with them. This response could be partly explained by the CP chemical composition. PMID:22548117

Distribution of the entomopathogenic nematodes from La Rioja (Northern Spain).

PubMed

Campos-Herrera, Raquel; Escuer, Miguel; Labrador, Sonia; Robertson, Lee; Barrios, Laura; Gutiérrez, Carmen

2007-06-01

Entomopathogenic nematodes (EPNs) distribution in natural areas and crop field edges in La Rioja (Northern Spain) has been studied taking into account environmental and physical-chemical soil factors. Five hundred soil samples from 100 sites of the most representative habitats were assayed for the presence of EPNs. The occurrence of EPNs statistically fitted to a negative binomial distribution, which pointed out that the natural distribution of these nematodes in La Rioja was in aggregates. There were no statistical differences (p < or = 0.05) in the abundance of EPNs to environmental and physical-chemical variables, although, there were statistical differences in the altitude, annual mean air temperature and rainfall, potential vegetation series and moisture percentage recovery frequency. Twenty-seven samples from 14 sites were positive for EPNs. From these samples, twenty isolates were identified to a species level and fifteen strains were selected: 11 Steinernema feltiae, two S. carpocapsae and two S. kraussei strains. S. kraussei was isolated from humid soils of cool and high altitude habitats and S. carpocapsae was found to occur in heavy soils of dry and temperate habitats. S. feltiae was the most common species with a wide range of altitude, temperature, rainfall, pH and soil moisture, although this species preferred sandy soils. The virulence of nematode strains were assessed using G. mellonella as insect host, recording the larval mortality percentage and the time to insect die, as well as the number of infective juveniles produced to evaluate the reproductive potential and the time tooks to leave the insect cadaver to determinate the infection cycle length. The ecological trends and biological results are discussed in relationship with their future use as biological control.

Conserving and enhancing biological control of nematodes.

PubMed

Timper, Patricia

2014-06-01

Conservation biological control is the modification of the environment or existing practices to protect and enhance antagonistic organisms to reduce damage from pests. This approach to biological control has received insufficient attention compared with inundative applications of microbial antagonists to control nematodes. This review provides examples of how production practices can enhance or diminish biological control of plant-parasitic nematodes and other soilborne pests. Antagonists of nematodes can be enhanced by providing supplementary food sources such as occurs when organic amendments are applied to soil. However, some organic amendments (e.g., manures and plants containing allelopathic compounds) can also be detrimental to nematode antagonists. Plant species and genotype can strongly influence the outcome of biological control. For instance, the susceptibility of the plant to the nematode can determine the effectiveness of control; good hosts will require greater levels of suppression than poor hosts. Plant genotype can also influence the degree of rhizosphere colonization and antibiotic production by antagonists, as well the expression of induced resistance by plants. Production practices such as crop rotation, fallow periods, tillage, and pesticide applications can directly disrupt populations of antagonistic organisms. These practices can also indirectly affect antagonists by reducing their primary nematode host. One of the challenges of conservation biological control is that practices intended to protect or enhance suppression of nematodes may not be effective in all field sites because they are dependent on indigenous antagonists. Ultimately, indicators will need to be identified, such as the presence of particular antagonists, which can guide decisions on where it is practical to use conservation biological control. Antagonists can also be applied to field sites in conjunction with conservation practices to improve the consistency, efficacy, and

Conserving and Enhancing Biological Control of Nematodes

PubMed Central

Timper, Patricia

2014-01-01

Conservation biological control is the modification of the environment or existing practices to protect and enhance antagonistic organisms to reduce damage from pests. This approach to biological control has received insufficient attention compared with inundative applications of microbial antagonists to control nematodes. This review provides examples of how production practices can enhance or diminish biological control of plant-parasitic nematodes and other soilborne pests. Antagonists of nematodes can be enhanced by providing supplementary food sources such as occurs when organic amendments are applied to soil. However, some organic amendments (e.g., manures and plants containing allelopathic compounds) can also be detrimental to nematode antagonists. Plant species and genotype can strongly influence the outcome of biological control. For instance, the susceptibility of the plant to the nematode can determine the effectiveness of control; good hosts will require greater levels of suppression than poor hosts. Plant genotype can also influence the degree of rhizosphere colonization and antibiotic production by antagonists, as well the expression of induced resistance by plants. Production practices such as crop rotation, fallow periods, tillage, and pesticide applications can directly disrupt populations of antagonistic organisms. These practices can also indirectly affect antagonists by reducing their primary nematode host. One of the challenges of conservation biological control is that practices intended to protect or enhance suppression of nematodes may not be effective in all field sites because they are dependent on indigenous antagonists. Ultimately, indicators will need to be identified, such as the presence of particular antagonists, which can guide decisions on where it is practical to use conservation biological control. Antagonists can also be applied to field sites in conjunction with conservation practices to improve the consistency, efficacy, and

Management and control of gastrointestinal nematodes in communal goat farms in Zimbabwe.

PubMed

Zvinorova, P I; Halimani, T E; Muchadeyi, F C; Katsande, S; Gusha, J; Dzama, K

2017-02-01

Goats are an important source of livelihood especially in smallholder communities. Infections with gastrointestinal nematodes (GIN) remain the most prevalent parasitic diseases affecting small ruminants. The study was conducted to assess management, the level of knowledge and control of gastrointestinal nematodes. Surveys were conducted in Chipinge, Shurugwi, Binga, Tsholotsho and Matobo districts, representing the five natural/agro-ecological regions (NR) in Zimbabwe. Data was collected in 135 households using a pre-tested semi-structured questionnaire. Results indicated that goats were ranked the most important livestock species, with high flock sizes in NR IV and V. Partitioning of roles was such that the adult males were involved in decision-making while females and children were involved in day-to-day management of animals. Farmers showed low levels of input use, with natural pasture (98.4%) being the main feed source and indigenous breeds (73.2%) being kept. Farmers ranked food and financial benefits as the main reasons for keeping goats. Gastrointestinal nematodes ranked the highest as the most common disease, with majority of farmers (57%) not controlling or treating animals and 63% of farmers not having knowledge on the spread of GIN. Access to veterinary services, anthelmintic class used and breeds used by the farmers had the highest effects on parasitic infections in households. Farmer education is required for capacitation of farmer in terms of disease prevention and control so as to improve goat production.

Large-scale diversification without genetic isolation in nematode symbionts of figs

PubMed Central

Susoy, Vladislav; Herrmann, Matthias; Kanzaki, Natsumi; Kruger, Meike; Nguyen, Chau N.; Rödelsperger, Christian; Röseler, Waltraud; Weiler, Christian; Giblin-Davis, Robin M.; Ragsdale, Erik J.; Sommer, Ralf J.

2016-01-01

Diversification is commonly understood to be the divergence of phenotypes accompanying that of lineages. In contrast, alternative phenotypes arising from a single genotype are almost exclusively limited to dimorphism in nature. We report a remarkable case of macroevolutionary-scale diversification without genetic divergence. Upon colonizing the island-like microecosystem of individual figs, symbiotic nematodes of the genus Pristionchus accumulated a polyphenism with up to five discrete adult morphotypes per species. By integrating laboratory and field experiments with extensive genotyping of individuals, including the analysis of 49 genomes from a single species, we show that rapid filling of potential ecological niches is possible without diversifying selection on genotypes. This uncoupling of morphological diversification and speciation in fig-associated nematodes has resulted from a remarkable expansion of discontinuous developmental plasticity. PMID:26824073

Biochemical changes in grape rootstocks resulted from humic acid treatments in relation to nematode infection.

PubMed

Kesba, Hosny H; El-Beltagi, Hossam S

2012-04-01

To investigate the effect of humic acid on nematode infected, resistant and susceptible grapes in relation to lipid peroxidation and antioxidant mechanisms on selected biochemical parameters known as proactive substances. The grape rootstocks, superior, superior/freedom and freedom were reacted differently to Meloidogyne incognita and Rotylenchulus reniformis according to rootstock progenitor. Two weeks after inoculation, two commercial products of humic acid were applied at the rate of (2, 4 mL or grams/plant) as soil drench. After 4 months, nematode soil populations were extracted and counted. A subsample of roots from each plant was stained and gall numbers, embedded stages per root were calculated, final population, nematode build up (Pf/Pi), average of eggs/eggmass were estimated. Subsamples of fresh root of each treatment were chemically analyzed. Freedom reduced significantly the nematode criteria and build up. Humic acid granules appeared to be more suppressive to nematode build up on superior and the higher dose on superior/freedom than liquid treatments. On freedom, all treatments reduced significantly the nematode build up regardless to the material nature. The higher dose was more effective than the lower one. As a result of humic acid applications, the malondialdehyde (MDA) and H2O2 contents were significantly reduced after humic acid treatments while the antioxidant compounds glutathione (GSH), ascorbic acid (ASA) and total phenol contents were significantly increased when compared with check. Antioxidant defense enzymes ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and polyphenol oxidase (PPO)showed significant increase in their specific activities in treated plants compared with nematode treated check. Humic acid treatments improve the yield of grape by increasing the contents of antioxidant compounds and the specific activities of antioxidant enzymes.

Biochemical changes in grape rootstocks resulted from humic acid treatments in relation to nematode infection

PubMed Central

Kesba, Hosny H; El-Beltagi, Hossam S

2012-01-01

Objective To investigate the effect of humic acid on nematode infected, resistant and susceptible grapes in relation to lipid peroxidation and antioxidant mechanisms on selected biochemical parameters known as proactive substances. Methods The grape rootstocks, superior, superior/freedom and freedom were reacted differently to Meloidogyne incognita and Rotylenchulus reniformis according to rootstock progenitor. Two weeks after inoculation, two commercial products of humic acid were applied at the rate of (2, 4 mL or grams/plant) as soil drench. After 4 months, nematode soil populations were extracted and counted. A subsample of roots from each plant was stained and gall numbers, embedded stages per root were calculated, final population, nematode build up (Pf/Pi), average of eggs/eggmass were estimated. Subsamples of fresh root of each treatment were chemically analyzed. Results Freedom reduced significantly the nematode criteria and build up. Humic acid granules appeared to be more suppressive to nematode build up on superior and the higher dose on superior/freedom than liquid treatments. On freedom, all treatments reduced significantly the nematode build up regardless to the material nature. The higher dose was more effective than the lower one. As a result of humic acid applications, the malondialdehyde (MDA) and H2O2 contents were significantly reduced after humic acid treatments while the antioxidant compounds glutathione (GSH), ascorbic acid (ASA) and total phenol contents were significantly increased when compared with check. Antioxidant defense enzymes ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) and polyphenol oxidase (PPO)showed significant increase in their specific activities in treated plants compared with nematode treated check. Conclusions Humic acid treatments improve the yield of grape by increasing the contents of antioxidant compounds and the specific activities of antioxidant enzymes. PMID:23569915

The elusive search for reniform nematode resistance in cotton

USDA-ARS?s Scientific Manuscript database

The reniform nematode (Rotylenchulus reniformis Linford and Oliveira) has emerged as the most important plant parasitic nematode of cotton in the US cotton belt. Success in the development of reniform nematode resistant upland cotton cultivars (Gossypium hirsutum L.) has not been realized despite ov...

Diverse Host-Seeking Behaviors of Skin-Penetrating Nematodes

PubMed Central

Castelletto, Michelle L.; Gang, Spencer S.; Okubo, Ryo P.; Tselikova, Anastassia A.; Nolan, Thomas J.; Platzer, Edward G.; Lok, James B.; Hallem, Elissa A.

2014-01-01

Skin-penetrating parasitic nematodes infect approximately one billion people worldwide and are responsible for some of the most common neglected tropical diseases. The infective larvae of skin-penetrating nematodes are thought to search for hosts using sensory cues, yet their host-seeking behavior is poorly understood. We conducted an in-depth analysis of host seeking in the skin-penetrating human parasite Strongyloides stercoralis, and compared its behavior to that of other parasitic nematodes. We found that Str. stercoralis is highly mobile relative to other parasitic nematodes and uses a cruising strategy for finding hosts. Str. stercoralis shows robust attraction to a diverse array of human skin and sweat odorants, most of which are known mosquito attractants. Olfactory preferences of Str. stercoralis vary across life stages, suggesting a mechanism by which host seeking is limited to infective larvae. A comparison of odor-driven behavior in Str. stercoralis and six other nematode species revealed that parasite olfactory preferences reflect host specificity rather than phylogeny, suggesting an important role for olfaction in host selection. Our results may enable the development of new strategies for combating harmful nematode infections. PMID:25121736

Effects of Php Gene-Associated versus Induced Resistance to Tobacco Cyst Nematode in Flue-Cured Tobacco

PubMed Central

Johnson, Charles S.; Eisenback, Jon D.

2009-01-01

Effects of the systemic acquired resistance (SAR)-inducing compound acibenzolar-S-methyl (ASM) and the plant-growth promoting rhizobacterial mixture Bacillus subtilis A13 and B. amyloliquefaciens IN937a (GB99+GB122) were assessed on the reproduction of a tobacco cyst nematode (TCN- Globodera tabacum solanacearum) under greenhouse conditions. Two sets of two independent experiments were conducted, each involving soil or root sampling. Soil sample experiments included flue-cured tobacco cultivars with (Php+: NC71 and NC102) and without (Php-: K326 and K346) a gene (Php) suppressing TCN parasitism. Root sample experiments examined TCN root parasitism of NC71 and K326. Cultivars possessing the Php gene (Php+) were compared with Php- cultivars to assess the effects of resistance mediated via Php gene vs. induced resistance to TCN. GB99+GB122 consistently reduced nematode reproductive ratio on both Php+ and Php- cultivars, but similar effects of ASM across Php- cultivars were less consistent. In addition, ASM application resulted in leaf yellowing and reduced root weight. GB99+GB122 consistently reduced nematode development in roots of both Php+ and Php- cultivars, while similar effects of ASM were frequently less consistent. The results of this study indicate that GB99+GB122 consistently reduced TCN reproduction in all flue-cured tobacco cultivars tested, while the effects of ASM were only consistent in Php+ cultivars. Under most circumstances, GB99+GB122 suppressed nematode reproduction more consistently than ASM compared to the untreated control. PMID:22736824

Testing deep-sea biodiversity paradigms on abyssal nematode genera and Acantholaimus species

NASA Astrophysics Data System (ADS)

Lins, Lidia; da Silva, Maria Cristina; Neres, Patrícia; Esteves, André Morgado; Vanreusel, Ann

2018-02-01

Biodiversity patterns in the deep sea have been extensively studied in the last decades. In this study, we investigated whether reputable concepts in deep-sea ecology also explain diversity and distribution patterns of nematode genera and species in the abyss. Among them, three paradigms were tackled: (1) the deep sea is a highly diverse environment at a local scale, while on a regional and even larger geographical scale, species and genus turnover is limited; (2) the biodiversity of deep-sea nematode communities changes with the nature and amount of organic matter input from the surface; and (3) patch-mosaic dynamics of the deep-sea environment drive local diversity. To test these hypotheses, diversity and density of nematode assemblages and of species of the genus Acantholaimus were studied along two abyssal E-W transects. These two transects were situated in the Southern Ocean ( 50°S) and the North Atlantic ( 10°N). Four different hierarchical scales were used to compare biodiversity: at the scale of cores, between stations from the same region, and between regions. Results revealed that the deep sea harbours a high diversity at a local scale (alpha diversity), but that turnover can be shaped by different environmental drivers. Therefore, these results question the second part of the paradigm about limited species turnover in the deep sea. Higher surface primary productivity was correlated with greater nematode densities, whereas diversity responses to the augmentation of surface productivity showed no trend. Areas subjected to a constant and low food input revealed similar nematode communities to other oligotrophic abyssal areas, while stations under high productivity were characterized by different dominant genera and Acantholaimus species, and by a generally low local diversity. Our results corroborate the species-energy hypothesis, where productivity can set a limit to the richness of an ecosystem. Finally, we observed no correlation between sediment

Plant actin cytoskeleton re-modeling by plant parasitic nematodes.

PubMed

Engler, Janice de Almeida; Rodiuc, Natalia; Smertenko, Andrei; Abad, Pierre

2010-03-01

The cytoskeleton is an important component of the plant's defense mechanism against the attack of pathogenic organisms. Plants however, are defenseless against parasitic root-knot and cyst nematodes and respond to the invasion by the development of a special feeding site that supplies the parasite with nutrients required for the completion of its life cycle. Recent studies of nematode invasion under treatment with cytoskeletal drugs and in mutant plants where normal functions of the cytoskeleton have been affected, demonstrate the importance of the cytoskeleton in the establishment of a feeding site and successful nematode reproduction. It appears that in the case of microfilaments, nematodes hijack the intracellular machinery that regulates actin dynamics and modulate the organization and properties of the actin filament network. Intervening with this process reduces the nematode infection efficiency and inhibits its life cycle. This discovery uncovers a new pathway that can be exploited for the protection of plants against nematodes.

Unraveling flp-11/flp-32 dichotomy in nematodes.

PubMed

Atkinson, Louise E; Miskelly, Iain R; Moffett, Christy L; McCoy, Ciaran J; Maule, Aaron G; Marks, Nikki J; Mousley, Angela

2016-10-01

FMRFamide-like peptide (FLP) signalling systems are core to nematode neuromuscular function. Novel drug discovery efforts associated with nematode FLP/FLP receptor biology are advanced through the accumulation of basic biological data that can reveal subtle complexities within the neuropeptidergic system. This study reports the characterisation of FMRFamide-like peptide encoding gene-11 (flp-11) and FMRFamide-like peptide encoding gene-32 (flp-32), two distinct flp genes which encode the analogous peptide, AMRN(A/S)LVRFamide, in multiple nematode species - the only known example of this phenomenon within the FLPergic system of nematodes. Using bioinformatics, in situ hybridisation, immunocytochemistry and behavioural assays we show that: (i) flp-11 and -32 are distinct flp genes expressed individually or in tandem across multiple nematode species, where they encode a highly similar peptide; (ii) flp-11 does not appear to be the most widely expressed flp in Caenorhabditis elegans; (iii) in species expressing both flp-11 and flp-32, flp-11 displays a conserved, restricted expression pattern across nematode clades and lifestyles; (iv) in species expressing both flp-11 and flp-32, flp-32 expression is more widespread and less conserved than flp-11; (v) in species expressing only flp-11, the flp-11 expression profile is more similar to the flp-32 profile observed in species expressing both; and (vi) FLP-11 peptides inhibit motor function in multiple nematode species. The biological significance and evolutionary origin of flp-11 and -32 peptide duplication remains unclear despite attempts to identify a common ancestor; this may become clearer as the availability of genomic data improves. This work provides insight into the complexity of the neuropeptidergic system in nematodes, and begins to examine how nematodes may compensate for structural neuronal simplicity. From a parasite control standpoint, this work underscores the importance of basic biological data, and has

Non-invasive assessment of parasitic nematode species diversity in wild Soay sheep using molecular markers.

PubMed

Wimmer, B; Craig, B H; Pilkington, J G; Pemberton, J M

2004-04-01

Considerable effort has been put into detecting and identifying parasitic nematodes in live ruminants, but to date most studies are limited to a small group of nematodes and/or to experimentally infected sheep. In this study, a PCR-based assay using species-specific primer pairs, located in the second internal transcribed spacer ribosomal DNA, was developed to identify nine different species from six different families of parasitic nematodes in a wild, unmanaged and naturally infected population of sheep. Each primer pair was tested for its specificity and sensitivity and it exclusively amplified the species it was designed for and exhibited a high degree of sensitivity. The method was applied to eggs and cultured larvae to identify the parasitic nematodes present in a pooled faecal sample from several host individuals with unknown parasite burden. To test detection reliability, a faecal sample from an individual with known parasite burden (through post-mortem analysis) was also examined. All species present could be correctly identified by PCR, but detecting very low levels and/or early stages of infection proved to be difficult. The method was also tested for its applicability to high through-put screening of faecal samples.

Resistance of Grape Rootstocks to Plant-parasitic Nematodes.

PubMed

Ferris, H; Zheng, L; Walker, M A

2012-12-01

Candidate grape rootstocks were selected through a rigorous screening program initiated with important sources of resistance to Meloidogyne pathotypes and to Xiphinema index in Muscadinia rotundifolia and Vitis species native to North America. Based on their rooting capability and horticultural characteristics, 200 candidates were selected from 5,000 progeny of multiple crosses between commercial grape rootstocks and wild grape species that exhibited resistance to nematodes. After a 15-year screening process, 13 selections emerged with either almost complete or complete combined resistance to M. incognita Race 3, M. incognita pathotype Harmony C, M. arenaria pathotype Harmony A, and X. index, important nematode pests of grapevines. Durability of this broad resistance was tested by challenging the selections with the target nematodes in combination and with the target nematodes in combinations with species not included in the screening process. Durability of resistance of the candidate rootstocks was also tested by exposure to the nematode communities of infested field soils from different locations. Breadth of resistance was determined on the basis of their host status to non-target nematodes, including Mesocriconema xenoplax, Pratylenchus vulnus, Tylenchulus semipenetrans and Paratylenchus hamatus. After a total of 204 separate trials, the rootstocks were released to the grape industry as UCD GRN1, UCD GRN2, UCD GRN3, UCD GRN4, and UCD GRN5. We provide a compilation of current knowledge of the host status of these five newly released rootstocks and of 27 other rootstock cultivars to plant-parasitic nematodes.

Novel RNA viruses within plant parasitic cyst nematodes.

PubMed

Ruark, Casey L; Gardner, Michael; Mitchum, Melissa G; Davis, Eric L; Sit, Tim L

2018-01-01

The study of invertebrate-and particularly nematode-viruses is emerging with the advancement of transcriptome sequencing. Five single-stranded RNA viruses have now been confirmed within the economically important soybean cyst nematode (SCN; Heterodera glycines). From previous research, we know these viruses to be widespread in greenhouse and field populations of SCN. Several of the SCN viruses were also confirmed within clover (H. trifolii) and beet (H. schachtii) cyst nematodes. In the presented study, we sequenced the transcriptomes of several inbred SCN populations and identified two previously undiscovered viral-like genomes. Both of these proposed viruses are negative-sense RNA viruses and have been named SCN nyami-like virus (NLV) and SCN bunya-like virus (BLV). Finally, we analyzed publicly available transcriptome data of two potato cyst nematode (PCN) species, Globodera pallida and G. rostochiensis. From these data, a third potential virus was discovered and called PCN picorna-like virus (PLV). PCN PLV is a positive-sense RNA virus, and to the best of our knowledge, is the first virus described within PCN. The presence of these novel viruses was confirmed via qRT-PCR, endpoint PCR, and Sanger sequencing with the exception of PCN PLV due to quarantine restrictions on the nematode host. While much work needs to be done to understand the biological and evolutionary significance of these viruses, they offer insight into nematode ecology and the possibility of novel nematode management strategies.

Resistance of Grape Rootstocks to Plant-parasitic Nematodes

PubMed Central

Ferris, H.; Zheng, L.; Walker, M. A.

2012-01-01

Candidate grape rootstocks were selected through a rigorous screening program initiated with important sources of resistance to Meloidogyne pathotypes and to Xiphinema index in Muscadinia rotundifolia and Vitis species native to North America. Based on their rooting capability and horticultural characteristics, 200 candidates were selected from 5,000 progeny of multiple crosses between commercial grape rootstocks and wild grape species that exhibited resistance to nematodes. After a 15-year screening process, 13 selections emerged with either almost complete or complete combined resistance to M. incognita Race 3, M. incognita pathotype Harmony C, M. arenaria pathotype Harmony A, and X. index, important nematode pests of grapevines. Durability of this broad resistance was tested by challenging the selections with the target nematodes in combination and with the target nematodes in combinations with species not included in the screening process. Durability of resistance of the candidate rootstocks was also tested by exposure to the nematode communities of infested field soils from different locations. Breadth of resistance was determined on the basis of their host status to non-target nematodes, including Mesocriconema xenoplax, Pratylenchus vulnus, Tylenchulus semipenetrans and Paratylenchus hamatus. After a total of 204 separate trials, the rootstocks were released to the grape industry as UCD GRN1, UCD GRN2, UCD GRN3, UCD GRN4, and UCD GRN5. We provide a compilation of current knowledge of the host status of these five newly released rootstocks and of 27 other rootstock cultivars to plant-parasitic nematodes. PMID:23482972

Stilbene epoxidation and detoxification in a Photorhabdus luminescens-nematode symbiosis

PubMed Central

Park, Hyun Bong; Sampathkumar, Parthasarathy; Perez, Corey E.; Lee, Joon Ha; Tran, Jeannie; Bonanno, Jeffrey B.; Hallem, Elissa A.; Almo, Steven C.; Crawford, Jason M.

2017-01-01

Members of the gammaproteobacterial Photorhabdus genus share mutualistic relationships with Heterorhabditis nematodes, and the pairs infect a wide swath of insect larvae. Photorhabdus species produce a family of stilbenes, with two major components being 3,5-dihydroxy-4-isopropyl-trans-stilbene (compound 1) and its stilbene epoxide (compound 2). This family of molecules harbors antimicrobial and immunosuppressive activities, and its pathway is responsible for producing a nematode “food signal” involved in nematode development. However, stilbene epoxidation biosynthesis and its biological roles remain unknown. Here, we identified an orphan protein (Plu2236) from Photorhabdus luminescens that catalyzes stilbene epoxidation. Structural, mutational, and biochemical analyses confirmed the enzyme adopts a fold common to FAD-dependent monooxygenases, contains a tightly bound FAD prosthetic group, and is required for the stereoselective epoxidation of compounds 1 and 2. The epoxidase gene was dispensable in a nematode-infective juvenile recovery assay, indicating the oxidized compound is not required for the food signal. The epoxide exhibited reduced cytotoxicity toward its producer, suggesting this may be a natural route for intracellular detoxification. In an insect infection model, we also observed two stilbene-derived metabolites that were dependent on the epoxidase. NMR, computational, and chemical degradation studies established their structures as new stilbene-l-proline conjugates, prolbenes A (compound 3) and B (compound 4). The prolbenes lacked immunosuppressive and antimicrobial activities compared with their stilbene substrates, suggesting a metabolite attenuation mechanism in the animal model. Collectively, our studies provide a structural view for stereoselective stilbene epoxidation and functionalization in an invertebrate animal infection model and provide new insights into stilbene cellular detoxification. PMID:28246174

Effect of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus.

PubMed

Nelson, R W; Scott-Moncrieff, J C; Feldman, E C; DeVries-Concannon, S E; Kass, P H; Davenport, D J; Kiernan, C T; Neal, L A

2000-04-01

To evaluate effects of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus. Randomized controlled crossover trial. 16 cats with naturally acquired diabetes mellitus. Cats were fed a diet high in insoluble fiber (HF) containing 12% cellulose (dry-matter basis) or a diet low in insoluble fiber (LF) for 24 weeks; they were fed the other diet for the subsequent 24 weeks. Caloric intake and insulin treatment were adjusted to maintain stable body weight and control of glycemia, respectively. Cats were allowed an adaptation period of 6 weeks after initiation of a diet, after which control of glycemia was evaluated at 6-week intervals for 18 weeks. Variables assessed included serum glucose concentration measured during the preprandial state, blood glycated hemoglobin concentration, serum glucose concentration measured at 2-hour intervals for 12 hours beginning at the time of the morning insulin injection, 12-hour mean serum glucose concentration, and mean fluctuation in serum glucose concentration from the 12-hour mean serum glucose concentration. Mean daily caloric intake, body weight, or daily insulin dosage did not differ significantly between cats when fed HF and LF diets. Mean preprandial serum glucose concentration, most post-prandial serum glucose concentrations, and the 12-hour mean serum glucose concentration were significantly lower when cats consumed the HF diet, compared with values when cats consumed the LF diet. These results support feeding a commercially available diet containing approximately 12% insoluble fiber (dry-matter basis) to cats with naturally acquired diabetes mellitus.

Entomopathogenic and plant pathogenic nematodes as opposing forces in agriculture.

PubMed

Kenney, Eric; Eleftherianos, Ioannis

2016-01-01

Plant-parasitic nematodes are responsible for substantial damages within the agriculture industry every year, which is a challenge that has thus far gone largely unimpeded. Chemical nematicides have been employed with varying degrees of success, but their implementation can be cumbersome, and furthermore they could potentially be neutralising an otherwise positive effect from the entomopathogenic nematodes that coexist with plant-parasitic nematodes in soil environments and provide protection for plants against insect pests. Recent research has explored the potential of employing entomopathogenic nematodes to protect plants from plant-parasitic nematodes, while providing their standard degree of protection against insects. The interactions involved are highly complex, due to both the three-organism system and the assortment of variables present in a soil environment, but a strong collection of evidence has accumulated regarding the suppressive capacity of certain entomopathogenic nematodes and their mutualistic bacteria, in the context of limiting the infectivity of plant-parasitic nematodes. Specific factors produced by certain entomopathogenic nematode complexes during the process of insect infection appear to have a selectively nematicidal, or at least repellant, effect on plant-parasitic nematodes. Using this information, an opportunity has formed to adapt this relationship to large-scale, field conditions and potentially relieve the agricultural industry of one of its most substantial burdens. Copyright © 2015 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Phytoparasitic Nematodes Adjacent to Established Strawberry Plantations

PubMed Central

Crow, R. V.; MacDonald, D. H.

1978-01-01

Plant-nematode populations associated with uncultivated vegetation, adjacent strawberry plants, and alternate crop sites were studied at three locations in Minnesota. At one site (Forest Lake), Paratylenchus projectus, Meloidogyne hapla, and Pratylenchus tenuis were frequently associated with the roots of native vegetation. These nematode species were also present in adjacent strawberry beds. Among alternate crops observed, oats and muskmelon usually supported the fewest nematodes although moderate densities of Xiphinema americanum and P. tenuis were found at one location in plots planted to oats. Pratylenchus tenuis was also found on rye at one location. PMID:19305841

A Treadmill to Localize, Exercise, and Measure the Propulsive Power of Nematodes

NASA Astrophysics Data System (ADS)

Yuan, Jinzhou; Chuan, Han-Sheng; Gnatt, Michael; Raizen, David; Bau, Haim

2011-11-01

The nematodes C. elegans is often used as model biological system to study the genetic basis of behavior, disease-progression, and aging, as well as to develop new therapies and screen drugs. On occasion, it is desirable to quantify the nematode's muscle power. Here, we present a kind of nematode treadmill. The device consists of a tapered conduit filled with aqueous solution. The conduit is subjected to a DC electric field and to pressure-driven flow directed from the narrow end. The nematode is inserted at the conduit's wide end. Directed by the electric field (through electrotaxis), the nematode swims deliberately upstream toward the negative pole. As the conduit narrows, the average fluid velocity and the drag force on the nematode increase. Eventually, the nematode arrives at an equilibrium position, at which its propulsive power balances the viscous drag force. The nematode's propulsive power is estimated with direct numerical simulations of the flow field around the nematode. The calculations utilize the experimentally imaged gait as a boundary condition. The device is useful to retain the nematode at a nearly fixed position for prolonged observations under a microscope, to keep the nematode exercising, and to estimate the nematode's power based on the conduit's width at the equilibrium position.

Granite Rock Outcrops: An Extreme Environment for Soil Nematodes?

PubMed Central

Austin, Erin; Semmens, Katharine; Parsons, Charles

2009-01-01

We studied soil nematode communities from the surface of granite flatrock outcrops in the eastern Piedmont region of the United States. The thin soils that develop here experience high light intensity and extreme fluctuations in temperature and moisture and host unique plant communities. We collected soils from outcrop microsites in Virginia (VA) and North Carolina (NC) in various stages of succession (Primitive, Minimal, and Mature) and compared soil properties and nematode communities to those of adjacent forest soils. Nematodes were present in most outcrop soils, with densities comparable to forest soils (P > 0.05). Nematode communities in Mature and Minimal soils had lower species richness than forest soils (P < 0.05) and contained more bacterial-feeders and fewer fungal-feeders (P < 0.05). Primitive soils contained either no nematodes (NC) or only a single species (Mesodorylaimus sp., VA). Nematode communities were similar between Mature and Minimal soils, according to trophic group representation, MI, PPI, EI, SI, and CI (P > 0.05). Forest soils had a higher PPI value (P < 0.05), but otherwise community indices were similar to outcrop soils (P > 0.05). Outcrop nematode communities failed to group together in a Bray-Curtis cluster analysis, indicating higher variability in community structure than the Forest soils, which did cluster together. A high proportion of the nematodes were extracted from outcrop soils in coiled form (33-89%), indicating that they used anhydrobiosis to persist in this unique environment. PMID:22661780

Assessment of nematode resistance in wheat transgenic plants expressing potato proteinase inhibitor (PIN2) gene.

PubMed

Vishnudasan, Dalia; Tripathi, M N; Rao, Uma; Khurana, Paramjit

2005-10-01

Serine proteinase inhibitors (IP's) are proteins found naturally in a wide range of plants with a significant role in the natural defense system of plants against herbivores. The question addressed in the present study involves assessing the ability of the serine proteinase inhibitor in combating nematode infestation. The present study involves engineering a plant serine proteinase inhibitor (pin2) gene into T. durum PDW215 by Agrobacterium-mediated transformation to combat cereal cyst nematode (Heterodera avenae) infestation. Putative T(0) transformants were screened and positive segregating lines analysed further for the study of the stable integration, expression and segregation of the genes. PCR, Southern analysis along with bar gene expression studies corroborate the stable integration pattern of the respective genes. The transformation efficiency is 3%, while the frequency of escapes was 35.71%. chi(2) analysis reveals the stable integration and segregation of the genes in both the T(1) and T(2) progeny lines. The PIN2 systemic expression confers satisfactory nematode resistance. The correlation analysis suggests that at p < 0.05 level of significance the relative proteinase inhibitor (PI) values show a direct positive correlation vis-à-vis plant height, plant seed weight and also the seed number.

Nematode and grape rootstock interactions including an improved understanding of tolerance.

PubMed

McKenry, M V; Anwar, Safdar A

2006-09-01

Sixteen cultivars of grape were screened over a two-year period in the presence or absence of 10 different nematode populations. Populations of Meloidogyne spp., Xiphinema index, and Mesocriconema xenoplax developed more rapidly and caused greater damage than populations of X. americanum and Tylenchulus semipenetrans. Populations of mixed Meloidogyne spp. having a history of feeding on grape were among the fastest developing populations. Tolerance to nematode parasitism appeared to be based on different mechanisms. Slow developing, less pathogenic nematode populations often stimulated vine growth, thus vines appeared to possess tolerance. Likewise, cultivars selected for nematode resistance often stimulated vine growth when fed upon by the nematode. However, tolerance sources that resulted from nematode resistance are vulnerable due to the occurrence of populations that break resistance mechanisms. Growth of cultivars with phylloxera (Daktalospharia vitifoliae) resistance was unchanged by the presence of nematodes, indicating that phylloxera resistance may provide a useful source of nematode relief. These and several additional sources of specific tolerance are discussed.

Nematode and Grape Rootstock Interactions Including an Improved Understanding of Tolerance

PubMed Central

McKenry, M.V.; Anwar, Safdar A.

2006-01-01

Sixteen cultivars of grape were screened over a two-year period in the presence or absence of 10 different nematode populations. Populations of Meloidogyne spp., Xiphinema index, and Mesocriconema xenoplax developed more rapidly and caused greater damage than populations of X. americanum and Tylenchulus semipenetrans. Populations of mixed Meloidogyne spp. having a history of feeding on grape were among the fastest developing populations. Tolerance to nematode parasitism appeared to be based on different mechanisms. Slow developing, less pathogenic nematode populations often stimulated vine growth, thus vines appeared to possess tolerance. Likewise, cultivars selected for nematode resistance often stimulated vine growth when fed upon by the nematode. However, tolerance sources that resulted from nematode resistance are vulnerable due to the occurrence of populations that break resistance mechanisms. Growth of cultivars with phylloxera (Daktalospharia vitifoliae) resistance was unchanged by the presence of nematodes, indicating that phylloxera resistance may provide a useful source of nematode relief. These and several additional sources of specific tolerance are discussed. PMID:19259534

Stem nematode counteracts plant resistance of aphids in alfalfa, Medicago sativa.

PubMed

Ramirez, Ricardo A; Spears, Lori R

2014-10-01

Plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. Generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. As plants are selected for resistance to one phytophagous organism type (insect vs. pathogen) in managed systems, it is not clear how this selection may affect community interactions. This study examined the effect of nematode-resistant varieties on aphid (Acyrthosiphon pisum) suppression, and then determined how infection by the stem nematode, Ditylenchus dipsaci, mediated ecological effects on aphids and on plant defense proteins. Four alfalfa (Medicago sativa) varieties were selected with resistance to nematodes only (+,-), aphids only (-,+), nematodes and aphids (+,+), and susceptibility to nematodes and aphids (-,-). Field and greenhouse experiments were conducted to isolate the effect of nematode infection and aphid abundance on each variety. We found that varieties resistant to nematode, regardless of aphid resistance, had the lowest aphid counts, suggesting possible cross-resistance. Aphid abundance, however, increased when plants were exposed to nematodes. Resistant varieties were associated with elevated saponins but these compounds were not affected by insect or pathogen feeding. Concentrations of peroxidases and trypsin inhibitors, however, were increased in nematode resistant varieties when exposed to nematodes and aphids, respectively. The patterns of plant defense were variable, and a combination of resistance traits and changes in nutrient availability may drive positive interactions between nematodes and aphids aboveground.

[Correlation between soil-transmitted nematode infections and children's growth].

PubMed

Wang, Xiao-Bing; Wang, Guo-Fei; Zhang, Lin-Xiu; Luo, Ren-Fu; Wang, Ju-Jun; Medina, Alexis; Eggleston, Karen; Rozelle, Scott; Smith, Scott

2013-06-01

To understand the infection status of soil-transmitted nematodes in southwest China and the correlation between soil-transmitted nematode infections and children's growth. The prevalence of soil-transmitted nematode infections was determined by Kato-Katz technique, and in part of the children, the examination of Enterobius vermicularis eggs was performed by using the cellophane swab method. The influencing factors were surveyed by using a standardized questionnaire. The relationship between soil-transmitted nematode infections and children's growth was analyzed by the ordinary least square (OLS) method. A total of 1 707 children were examined, with a soil-transmitted nematode infection rate of 22.2%. The results of OLS analysis showed that there existed the negative correlation between soil-transmitted nematode infections and the indexes of children's growth including BMI, the weight-for-age Z score and height-for-age Z score. Furthermore, other correlated variables included the age, gender, educational level of mother and raising livestock and poultry, etc. Children' s retardation is still a serious issue in the southwest poor areas of China and correlated with the infections of soil-transmitted nematodes. For improving children's growth, it is greatly significant to enhance the deworming and health education about parasitic diseases in mothers.

Management of cereal cyst nematodes, Heterodera spp., in Norway.

PubMed

Holgado, R; Andersson, S; Magnusson, C

2006-01-01

Cereal cyst nematodes, Heterodera spp., are known worldwide as parasites of cereals and grasses. Surveys of cereal fields in Norway have revealed that nematodes belonging to the H. avenae complex occur throughout the country, and that H. avenae (the oat cyst nematode) is the most common species, followed by H. filipjevi (the rye cyst nematode). Both species are of economic importance in Scandinavia. H. avenae has been found in two common pathotypes, Ha 11 and Ha 12. Work in Sweden, however, has detected three additional pathotypes, H. avenae "Knislinge", H. avenae "Ringsisen" and H. avenae "Våxtorp". These pathotypes were found also in the Norwegian surveys. In Sweden H. filipjevi has two pathotypes, "East" and "West". In Norway, only pathotype "West" has been detected so far. Nematode management practices must be based on the knowledge of the relationship between initial nematode density and yield, the population dynamics, and the measures capable of reducing or keeping the population density below the threshold for economic damage. Crop rotation and the use of cultivars with resistance are important measures for controlling cereal cyst nematodes. Several cereal cultivars with resistance to H. avenae are on the market. As to H. filipjevi, resistance may be found in some commercial cultivars, although no intentional breeding for resistance against this nematode species has been attempted. In 2004 and 2005 the majority of the cereal cultivars on the Norwegian market were tested for susceptibility/resistance towards H. avenae pathotype Ha 11, H. avenae pathotype "Våxtorp" and H. filipjevi pathotype "West". Management systems, based on careful nematode identification and good knowledge of appropriate resistant cultivars, are in operation in Norway. Resistant barley is generally recommended when nematode populations are high due to its high tolerance compared to resistant oats. Farmers implementing this program have reported increased cereal yields on the average of

Apoplastic Venom Allergen-like Proteins of Cyst Nematodes Modulate the Activation of Basal Plant Innate Immunity by Cell Surface Receptors

PubMed Central

Lozano-Torres, Jose L.; Wilbers, Ruud H. P.; Warmerdam, Sonja; Finkers-Tomczak, Anna; Diaz-Granados, Amalia; van Schaik, Casper C.; Helder, Johannes; Bakker, Jaap; Goverse, Aska; Schots, Arjen; Smant, Geert

2014-01-01

Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize

Apoplastic venom allergen-like proteins of cyst nematodes modulate the activation of basal plant innate immunity by cell surface receptors.

PubMed

Lozano-Torres, Jose L; Wilbers, Ruud H P; Warmerdam, Sonja; Finkers-Tomczak, Anna; Diaz-Granados, Amalia; van Schaik, Casper C; Helder, Johannes; Bakker, Jaap; Goverse, Aska; Schots, Arjen; Smant, Geert

2014-12-01

Despite causing considerable damage to host tissue during the onset of parasitism, nematodes establish remarkably persistent infections in both animals and plants. It is thought that an elaborate repertoire of effector proteins in nematode secretions suppresses damage-triggered immune responses of the host. However, the nature and mode of action of most immunomodulatory compounds in nematode secretions are not well understood. Here, we show that venom allergen-like proteins of plant-parasitic nematodes selectively suppress host immunity mediated by surface-localized immune receptors. Venom allergen-like proteins are uniquely conserved in secretions of all animal- and plant-parasitic nematodes studied to date, but their role during the onset of parasitism has thus far remained elusive. Knocking-down the expression of the venom allergen-like protein Gr-VAP1 severely hampered the infectivity of the potato cyst nematode Globodera rostochiensis. By contrast, heterologous expression of Gr-VAP1 and two other venom allergen-like proteins from the beet cyst nematode Heterodera schachtii in plants resulted in the loss of basal immunity to multiple unrelated pathogens. The modulation of basal immunity by ectopic venom allergen-like proteins in Arabidopsis thaliana involved extracellular protease-based host defenses and non-photochemical quenching in chloroplasts. Non-photochemical quenching regulates the initiation of the defense-related programmed cell death, the onset of which was commonly suppressed by venom allergen-like proteins from G. rostochiensis, H. schachtii, and the root-knot nematode Meloidogyne incognita. Surprisingly, these venom allergen-like proteins only affected the programmed cell death mediated by surface-localized immune receptors. Furthermore, the delivery of venom allergen-like proteins into host tissue coincides with the enzymatic breakdown of plant cell walls by migratory nematodes. We, therefore, conclude that parasitic nematodes most likely utilize

Anthelmintic resistance in equine nematodes

PubMed Central

Matthews, Jacqueline B.

2014-01-01

Anthelmintics have been applied indiscriminately to control horse nematodes for over 40 years. Three broad-spectrum anthelmintic classes are currently registered for nematode control in horses: benzimidazoles (fenbendazole, oxibendazole), tetrahydropyrimidines (pyrantel) and macrocyclic lactones (ivermectin, moxidectin). Generally, control strategies have focused on nematode egg suppression regimens that involve the frequent application of anthelmintics to all horses at intervals based on strongyle egg reappearance periods after treatment. The widespread use of such programmes has substantially reduced clinical disease, especially that associated with large strongyle species; however, high treatment frequency has led to considerable selection pressure for anthelmintic resistance, particularly in cyathostomin species. Field studies published over the last decade indicate that benzimidazole resistance is widespread globally in cyathostomins and there are also many reports of resistance to pyrantel in these worms. Cyathostomin resistance to macrocyclic lactone compounds is emerging, principally measured as a reduction in strongyle egg reappearance time observed after treatment. Ivermectin resistance is a further concern in the small intestinal nematode, Parascaris equorum, an important pathogen of foals. These issues indicate that horse nematodes must now be controlled using methods less dependent on anthelmintic use and more reliant on management practices designed to reduce the force of infection in the environment. Such strategies include improved grazing management integrated with targeted anthelmintic administration involving faecal egg count (FEC)-directed treatments. The latter require that the supporting diagnostic tests available are robust and practically applicable. Recent research has focused on maximising the value of FEC analysis in horses and on optimizing protocols for anthelmintic efficacy testing. Other studies have sought to develop diagnostics

Biotechnological application of functional genomics towards plant-parasitic nematode control.

PubMed

Li, Jiarui; Todd, Timothy C; Lee, Junghoon; Trick, Harold N

2011-12-01

Plant-parasitic nematodes are primary biotic factors limiting the crop production. Current nematode control strategies include nematicides, crop rotation and resistant cultivars, but each has serious limitations. RNA interference (RNAi) represents a major breakthrough in the application of functional genomics for plant-parasitic nematode control. RNAi-induced suppression of numerous genes essential for nematode development, reproduction or parasitism has been demonstrated, highlighting the considerable potential for using this strategy to control damaging pest populations. In an effort to find more suitable and effective gene targets for silencing, researchers are employing functional genomics methodologies, including genome sequencing and transcriptome profiling. Microarrays have been used for studying the interactions between nematodes and plant roots and to measure both plants and nematodes transcripts. Furthermore, laser capture microdissection has been applied for the precise dissection of nematode feeding sites (syncytia) to allow the study of gene expression specifically in syncytia. In the near future, small RNA sequencing techniques will provide more direct information for elucidating small RNA regulatory mechanisms in plants and specific gene silencing using artificial microRNAs should further improve the potential of targeted gene silencing as a strategy for nematode management. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

Changes in soil nematode communities under the impact of fertilizers

NASA Astrophysics Data System (ADS)

Gruzdeva, L. I.; Matveeva, E. M.; Kovalenko, T. E.

2007-06-01

Changes taking place in the communities of soil nematodes of an artificially sown meadow under the impact of annually applied mineral fertilizers have been studied in a field experiment for nine years. It is shown that changes in the species composition, trophic structure, and numbers of nematodes from different genera depend on the fertilizer applied and on the competitiveness of the plant species grown. The spectra of nematode genera sensitive to the complete mineral fertilizer (NPK) and to the particular nutrients have been identified with the use of a number of parameters, including the maturity index of nematode communities, the biotope preferences of the particular nematode genera, and the general pattern of nematode habitats. The results obtained in this study can be used to assess the effect of mineral fertilizers on the soil fauna and to suggest optimum application rates of mineral fertilizers ensuring the sustainable development of meadow herbs. The use of the data on the trophic structure of nematode communities for predicting the ways of organic matter decomposition in the soil is discussed.

Prevalence and intensity of nematode parasites in Wisconsin ermine.

PubMed

Dubay, Shelli; Buchholz, Matthew J; Lisiecki, Robert; Huspeni, Todd; Ginnett, Tim; Haen, Luke; Borsdorf, Phil

2014-10-01

In the midwestern United States, ermine ( Mustela erminea ) are economically important because they are legally harvested for pelts. Information on parasites of ermine is lacking, and the effects that nematode parasites have on body condition of ermine hosts are unknown. We identified Skrjabingylus nasicola and Filaroides martis in ermine trapped from 2007 to 2013 from 6 counties in Wisconsin. Small mammals, commonly consumed by ermine, serve as paratenic hosts for both parasites. Our goal was to identify how age and sex of ermine, along with year, influence nematode parasitism. We also investigated how infection affected body condition for male and female ermine using body mass standardized by length as an index of body condition. We commonly found S. nasicola and F. martis in male and female ermine, but both prevalence and intensity of infection were higher for males. Relative to juveniles (<1 yr), adult (>1 yr) male ermine did not exhibit significantly higher intensity or prevalence of either parasite. We found that body condition was not compromised by infection for either sex, and intensity of S. nasicola and prevalence of F. martis were highest during the 2010-2011 trapping season. Of the 6 yr studied, precipitation was highest during the summer before the 2010-2011 season, and increased precipitation can cause increases in populations of gastropod intermediate hosts. We think that several distinct natural history components, namely, mating structure, diet, and metabolic rate, influence nematode parasitism in ermine.

Hsp-90 and the biology of nematodes

PubMed Central

Him, Nik AIIN; Gillan, Victoria; Emes, Richard D; Maitland, Kirsty; Devaney, Eileen

2009-01-01

Background Hsp-90 from the free-living nematode Caenorhabditis elegans is unique in that it fails to bind to the specific Hsp-90 inhibitor, geldanamycin (GA). Here we surveyed 24 different free-living or parasitic nematodes with the aim of determining whether C. elegans Hsp-90 was the exception or the norm amongst the nematodes. We combined these data with codon evolution models in an attempt to identify whether hsp-90 from GA-binding and non-binding species has evolved under different evolutionary constraints. Results We show that GA-binding is associated with life history: free-living nematodes and those parasitic species with free-living larval stages failed to bind GA. In contrast, obligate parasites and those worms in which the free-living stage in the environment is enclosed within a resistant egg, possess a GA-binding Hsp-90. We analysed Hsp-90 sequences from fifteen nematode species to determine whether nematode hsp-90s have undergone adaptive evolution that influences GA-binding. Our data provide evidence of rapid diversifying selection in the evolution of the hsp-90 gene along three separate lineages, and identified a number of residues showing significant evidence of adaptive evolution. However, we were unable to prove that the selection observed is correlated with the ability to bind geldanamycin or not. Conclusion Hsp-90 is a multi-functional protein and the rapid evolution of the hsp-90 gene presumably correlates with other key cellular functions. Factors other than primary amino acid sequence may influence the ability of Hsp-90 to bind to geldanamycin. PMID:19849843

Developmental plasticity and the evolution of parasitism in an unusual nematode, Parastrongyloides trichosuri.

PubMed

Stasiuk, Susan J; Scott, Maxwell J; Grant, Warwick N

2012-01-03

Parasitism is an important life history strategy in many metazoan taxa. This is particularly true of the Phylum Nematoda, in which parasitism has evolved independently at least nine times. The apparent ease with which parasitism has evolved amongst nematodes may, in part, be due to a feature of nematode development acting as a pre-adaptation for the transition from a free-living to a parasitic life history. One candidate pre-adaptive feature for evolution in terrestrial nematodes is the dauer larva, a developmentally arrested morph formed in response to environmental signals. We investigated the role of dauer development in the nematode, Parastrongyloides trichosuri, which has retained a complete free-living life cycle in addition to a life cycle as a mammalian gastrointestinal parasite. We show that the developmental switch between these life histories is sensitive to the same environmental cues as dauer arrest in free-living nematodes, including sensitivity to a chemical cue produced by the free-living stages. Furthermore, we show that genetic variation for the sensitivity of the cue(s) exists in natural populations of P. trichosuri, such that we derived inbred lines that were largely insensitive to the cue and other lines that were supersensitive to the cue. For this parasitic clade, and perhaps more widely in the phylum, the evolution of parasitism co-opted the dauer switch of a free-living ancestor. This lends direct support to the hypothesis that the switch to developmental arrest in the dauer larva acted as a pre-adaptation for the evolution of parasitism, and suggests that the sensory transduction machinery downstream of the cue may have been similarly co-opted and modified.

Developmental plasticity and the evolution of parasitism in an unusual nematode, Parastrongyloides trichosuri

PubMed Central

2012-01-01

Background Parasitism is an important life history strategy in many metazoan taxa. This is particularly true of the Phylum Nematoda, in which parasitism has evolved independently at least nine times. The apparent ease with which parasitism has evolved amongst nematodes may, in part, be due to a feature of nematode development acting as a pre-adaptation for the transition from a free-living to a parasitic life history. One candidate pre-adaptive feature for evolution in terrestrial nematodes is the dauer larva, a developmentally arrested morph formed in response to environmental signals. Results We investigated the role of dauer development in the nematode, Parastrongyloides trichosuri, which has retained a complete free-living life cycle in addition to a life cycle as a mammalian gastrointestinal parasite. We show that the developmental switch between these life histories is sensitive to the same environmental cues as dauer arrest in free-living nematodes, including sensitivity to a chemical cue produced by the free-living stages. Furthermore, we show that genetic variation for the sensitivity of the cue(s) exists in natural populations of P. trichosuri, such that we derived inbred lines that were largely insensitive to the cue and other lines that were supersensitive to the cue. Conclusions For this parasitic clade, and perhaps more widely in the phylum, the evolution of parasitism co-opted the dauer switch of a free-living ancestor. This lends direct support to the hypothesis that the switch to developmental arrest in the dauer larva acted as a pre-adaptation for the evolution of parasitism, and suggests that the sensory transduction machinery downstream of the cue may have been similarly co-opted and modified. PMID:22214222

Challenges for mass production of nematodes in submerged culture.

PubMed

de la Torre, Mayra

2003-08-01

Nematodes of Steinernema and Heterorhabditis genera are used as agents in insect biocontrol programs. They are associated with specific bacteria which are also involved in the mechanism of pathogenicity and which are consumed by nematodes as living food. S. feltiae has various developmental stages in its life cycle, including four juvenile stages, adults and the free living form. During mating, males coil themselves around the female, which is around 1 cm long. Successful commercialization of nematode-bacteria biocontrol products depends on the ability to produce sufficient quantities of these products at competitive prices for a full pest control program. This could be feasible if high cell density submerged cultures are designed and implemented; however, major problems related to nematodes mass production in a bioreactor remain unsolved due to the lack of knowledge about the physiological aspects of the nematode, bacteria and nematode-bacteria association, interaction between the three phases present in the bioreactor (liquid, gas, nematodes-bacteria), possibility of mating under hydrodynamic stress conditions, etc. We have found that the two most important engineering aspects to take into account the mass propagation of nematodes are oxygen transfer rate and hydrodynamics to allow mating and to avoid mechanical damage of juveniles in stage 2. This article focuses on several aspects related to the fermentation system such as kinetics of growth, shear stress, hydrodynamics fields in the bioreactor and oxygen demand. Also, results published by other groups, together with those of our own, will be discussed in relation to the main challenges found during the fermentation process.

Nematode taxonomy: from morphology to metabarcoding

NASA Astrophysics Data System (ADS)

Ahmed, M.; Sapp, M.; Prior, T.; Karssen, G.; Back, M.

2015-11-01

Nematodes represent a species rich and morphologically diverse group of metazoans inhabiting both aquatic and terrestrial environments. Their role as biological indicators and as key players in nutrient cycling has been well documented. Some groups of nematodes are also known to cause significant losses to crop production. In spite of this, knowledge of their diversity is still limited due to the difficulty in achieving species identification using morphological characters. Molecular methodology has provided very useful means of circumventing the numerous limitations associated with classical morphology based identification. We discuss herein the history and the progress made within the field of nematode systematics, the limitations of classical taxonomy and how the advent of high throughput sequencing is facilitating advanced ecological and molecular studies.

Theory of the locomotion of nematodes

PubMed Central

Niebur, Ernst; Erdös, Paul

1991-01-01

We develop a model of the undulatory locomotion of nematodes, in particular that of Caenorhabditis elegans, based on mechanics. The model takes into account the most important forces acting on a moving worm and allows the computer simulation of a creeping nematode. These forces are produced by the interior pressure in the liquid-filled body cavity, the elasticity of the cuticle, the excitation of certain sets of muscles and the friction between the body and its support. We propose that muscle excitation patterns can be generated by stretch receptor control. By solving numerically the equations of motion of the model of the nematode, we demonstrate that these muscle excitation patterns are suitable for the propulsion of the animal. PMID:19431807

Parasitic nematode interactions with mammals and plants.

PubMed

Jasmer, Douglas P; Goverse, Aska; Smant, Geert

2003-01-01

Parasitic nematodes that infect humans, animals, and plants cause serious diseases that are deleterious to human health and agricultural productivity. Chemical and biological control methods have reduced the impact of these parasites. However, surviving environmental stages lead to persistent reinfection of host species. In addition, development of resistance to nematicides and anthelmintics by these parasites and reduced availability of some nematicides, for environmental protection, pose significant obstacles for current and future prospects of effective parasite control. Due to marked differences in host species, research on animal and plant parasitic nematodes often proceeds independently. Despite the differences between animals and plants, basic cellular properties are shared among these host organisms. Some common properties may be important for mechanisms [homologous or convergent (homoplastic)] by which nematodes successfully infect these diverse hosts or by which animal and plant hosts resist infections by these pathogens. Here we compare host/parasite interactions between plant parasitic nematodes (PPN) and animal parasitic nematodes, with an emphasis on mammalian hosts (MPN). Similarities and differences are considered in the context of progress on molecular dissection of these interactions. A comprehensive coverage is not possible in the space allotted. Instead, an illustrative approach is used to establish examples that, it is hoped, exemplify the value of the comparative approach.

NemaPath: online exploration of KEGG-based metabolic pathways for nematodes

PubMed Central

Wylie, Todd; Martin, John; Abubucker, Sahar; Yin, Yong; Messina, David; Wang, Zhengyuan; McCarter, James P; Mitreva, Makedonka

2008-01-01

Background Nematode.net is a web-accessible resource for investigating gene sequences from parasitic and free-living nematode genomes. Beyond the well-characterized model nematode C. elegans, over 500,000 expressed sequence tags (ESTs) and nearly 600,000 genome survey sequences (GSSs) have been generated from 36 nematode species as part of the Parasitic Nematode Genomics Program undertaken by the Genome Center at Washington University School of Medicine. However, these sequencing data are not present in most publicly available protein databases, which only include sequences in Swiss-Prot. Swiss-Prot, in turn, relies on GenBank/Embl/DDJP for predicted proteins from complete genomes or full-length proteins. Description Here we present the NemaPath pathway server, a web-based pathway-level visualization tool for navigating putative metabolic pathways for over 30 nematode species, including 27 parasites. The NemaPath approach consists of two parts: 1) a backend tool to align and evaluate nematode genomic sequences (curated EST contigs) against the annotated Kyoto Encyclopedia of Genes and Genomes (KEGG) protein database; 2) a web viewing application that displays annotated KEGG pathway maps based on desired confidence levels of primary sequence similarity as defined by a user. NemaPath also provides cross-referenced access to nematode genome information provided by other tools available on Nematode.net, including: detailed NemaGene EST cluster information; putative translations; GBrowse EST cluster views; links from nematode data to external databases for corresponding synonymous C. elegans counterparts, subject matches in KEGG's gene database, and also KEGG Ontology (KO) identification. Conclusion The NemaPath server hosts metabolic pathway mappings for 30 nematode species and is available on the World Wide Web at . The nematode source sequences used for the metabolic pathway mappings are available via FTP , as provided by the Genome Center at Washington University

[Nematodes (Nematoda) from bats (Chiroptera) of the Samarskaya Luka Peninsula (Russia)].

PubMed

Kirillova, N Iu; Kirillov, A A; Vekhnik, V P

2008-01-01

Fauna of parasitic nematodes from Chiroptera of the Samarskaya Luka has been studied. Seven nematode species has been recorded. Numbers of host specimens, indices of extensiveness and intensiveness of the invasion, parasite abundance, and brief characteristics of the nematode species are given. Some nematode species were for the first time recorded in bats of Russia.

Nematode-bacterium symbioses--cooperation and conflict revealed in the "omics" age.

PubMed

Murfin, Kristen E; Dillman, Adler R; Foster, Jeremy M; Bulgheresi, Silvia; Slatko, Barton E; Sternberg, Paul W; Goodrich-Blair, Heidi

2012-08-01

Nematodes are ubiquitous organisms that have a significant global impact on ecosystems, economies, agriculture, and human health. The applied importance of nematodes and the experimental tractability of many species have promoted their use as models in various research areas, including developmental biology, evolutionary biology, ecology, and animal-bacterium interactions. Nematodes are particularly well suited for the investigation of host associations with bacteria because all nematodes have interacted with bacteria during their evolutionary history and engage in a variety of association types. Interactions between nematodes and bacteria can be positive (mutualistic) or negative (pathogenic/parasitic) and may be transient or stably maintained (symbiotic). Furthermore, since many mechanistic aspects of nematode-bacterium interactions are conserved, their study can provide broader insights into other types of associations, including those relevant to human diseases. Recently, genome-scale studies have been applied to diverse nematode-bacterial interactions and have helped reveal mechanisms of communication and exchange between the associated partners. In addition to providing specific information about the system under investigation, these studies also have helped inform our understanding of genome evolution, mutualism, and innate immunity. In this review we discuss the importance and diversity of nematodes, "omics"' studies in nematode-bacterial systems, and the wider implications of the findings.

Nematode-Bacterium Symbioses - Cooperation and Conflict Revealed in the 'Omics' Age

PubMed Central

Murfin, Kristen E.; Dillman, Adler R.; Foster, Jeremy M.; Bulgheresi, Silvia; Slatko, Barton E.; Sternberg, Paul W.; Goodrich-Blair, Heidi

2012-01-01

Nematodes are ubiquitous organisms that have a significant global impact on ecosystems, economies, agriculture, and human health. The applied importance of nematodes and the experimental tractability of many species have promoted their use as models in various research areas, including developmental biology, evolutionary biology, ecology, and animal-bacterium interactions. Nematodes are particularly well suited for investigating host associations with bacteria because all nematodes have interacted with bacteria during their evolutionary history and engage in a diversity of association types. Interactions between nematodes and bacteria can be positive (mutualistic) or negative (pathogenic/parasitic) and may be transient or stably maintained (symbiotic). Furthermore, since many mechanistic aspects of nematode-bacterium interactions are conserved their study can provide broader insights into other types of associations, including those relevant to human diseases. Recently, genome-scale studies have been applied to diverse nematode-bacterial interactions, and have helped reveal mechanisms of communication and exchange between the associated partners. In addition to providing specific information about the system under investigation, these studies also have helped inform our understanding of genome evolution, mutualism, and innate immunity. In this review we will discuss the importance and diversity of nematodes, 'omics' studies in nematode-bacterial systems, and the wider implications of the findings. PMID:22983035

Pack hunting by a common soil amoeba on nematodes.

PubMed

Geisen, Stefan; Rosengarten, Jamila; Koller, Robert; Mulder, Christian; Urich, Tim; Bonkowski, Michael

2015-11-01

Soils host the most complex communities on Earth, including the most diverse and abundant eukaryotes, i.e. heterotrophic protists. Protists are generally considered as bacterivores, but evidence for negative interactions with nematodes both from laboratory and field studies exist. However, direct impacts of protists on nematodes remain unknown. We isolated the soil-borne testate amoeba Cryptodifflugia operculata and found a highly specialized and effective pack-hunting strategy to prey on bacterivorous nematodes. Enhanced reproduction in presence of prey nematodes suggests a beneficial predatory life history of these omnivorous soil amoebae. Cryptodifflugia operculata appears to selectively impact the nematode community composition as reductions of nematode numbers were species specific. Furthermore, we investigated 12 soil metatranscriptomes from five distinct locations throughout Europe for 18S ribosomal RNA transcripts of C. operculata. The presence of C. operculata transcripts in all samples, representing up to 4% of the active protist community, indicates a potential ecological importance of nematophagy performed by C. operculata in soil food webs. The unique pack-hunting strategy on nematodes that was previously unknown from protists, together with molecular evidence that these pack hunters are likely to be abundant and widespread in soils, imply a considerable importance of the hitherto neglected trophic link 'nematophagous protists' in soil food webs. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

The activation and suppression of plant innate immunity by parasitic nematodes.

PubMed

Goverse, Aska; Smant, Geert

2014-01-01

Plant-parasitic nematodes engage in prolonged and intimate relationships with their host plants, often involving complex alterations in host cell morphology and function. It is puzzling how nematodes can achieve this, seemingly without activating the innate immune system of their hosts. Secretions released by infective juvenile nematodes are thought to be crucial for host invasion, for nematode migration inside plants, and for feeding on host cells. In the past, much of the research focused on the manipulation of developmental pathways in host plants by plant-parasitic nematodes. However, recent findings demonstrate that plant-parasitic nematodes also deliver effectors into the apoplast and cytoplasm of host cells to suppress plant defense responses. In this review, we describe the current insights in the molecular and cellular mechanisms underlying the activation and suppression of host innate immunity by plant-parasitic nematodes along seven critical evolutionary and developmental transitions in plant parasitism.

Induction of SA-signaling pathway and ethylene biosynthesis in Trichoderma harzianum-treated tomato plants after infection of the root-knot nematode Meloidogyne incognita.

PubMed

Leonetti, Paola; Zonno, Maria Chiara; Molinari, Sergio; Altomare, Claudio

2017-04-01

Salicylic acid-signaling pathway and ethylene biosynthesis were induced in tomato treated with Trichoderma harzianum when infected by root-knot nematodes and limited the infection by activation of SAR and ethylene production. Soil pre-treatment with Trichoderma harzianum (Th) strains ITEM 908 (T908) and T908-5 decreased susceptibility of tomato to Meloidogyne incognita, as assessed by restriction in nematode reproduction and development. The effect of T. harzianum treatments on plant defense was detected by monitoring the expression of the genes PR-1/PR-5 and JERF3/ACO, markers of the SA- and JA/ET-dependent signaling pathways, respectively. The compatible nematode-plant interaction in absence of fungi caused a marked suppression of PR-1, PR-5, and ACO gene expressions, either locally or systemically, whilst expression of JERF3 gene resulted unaffected. Conversely, when plants were pre-treated with Th-strains, over-expression of PR-1, PR-5, and ACO genes was observed in roots 5 days after nematode inoculation. JERF3 gene expression did not change in Th-colonized plants challenged with nematodes. In the absence of nematodes, Trichoderma-root interaction was characterized by the inhibition of both SA-dependent signaling pathway and ET biosynthesis, and, in the case of PR-1 and ACO genes, this inhibition was systemic. JERF3 gene expression was systemically restricted only at the very early stages of plant-fungi interaction. Data presented indicate that Th-colonization primed roots for Systemic Acquired Resistance (SAR) against root-knot nematodes and reacted to nematode infection more efficiently than untreated plants. Such a response probably involves also activation of ET production, through an augmented transcription of the ACO gene, which encodes for the enzyme catalyzing the last step of ET biosynthesis. JA signaling and Induced Systemic Resistance (ISR) do not seem to be involved in the biocontrol action of the tested Th-strains against RKNs.

Survey of nematodes associated with terrestrial slugs in Norway.

PubMed

Ross, J L; Ivanova, E S; Hatteland, B A; Brurberg, M B; Haukeland, S

2016-09-01

A survey of nematodes associated with terrestrial slugs was conducted for the first time in Norway. A total of 611 terrestrial slugs were collected from 32 sample sites. Slugs were identified by means of morphological examination, dissection of genitalia and molecular analysis using mitochondrial DNA. Twelve slug species were identified, representing four different slug families. Internal nematodes were identified by means of morphological analysis and the sequencing of the 18S rRNA gene. Of the sample sites studied, 62.5% were found to be positive for nematode parasites, with 18.7% of all slugs discovered being infected. Five nematode species were identified in this study: Alloionema appendiculatum, Agfa flexilis, Angiostoma limacis, Angiostoma sp. and Phasmarhabditis hermaphrodita. Of these species, only one nematode was previously undescribed (Angiostoma sp.). This is the first record of the presence of A. appendiculatum, A. flexilis and A. limacis in Norway.

Heterozygote deficits in cyst plant-parasitic nematodes: possible causes and consequences.

PubMed

Montarry, Josselin; Jan, Pierre-Loup; Gracianne, Cecile; Overall, Andrew D J; Bardou-Valette, Sylvie; Olivier, Eric; Fournet, Sylvain; Grenier, Eric; Petit, Eric J

2015-04-01

Deviations of genotypic frequencies from Hardy-Weinberg equilibrium (HWE) expectations could reveal important aspects of the biology of populations. Deviations from HWE due to heterozygote deficits have been recorded for three plant-parasitic nematode species. However, it has never been determined whether the observed deficits were due (i) to the presence of null alleles, (ii) to a high level of consanguinity and/or (iii) to a Wahlund effect. The aim of the present work was, while taking into the possible confounding effect of null alleles, to disentangle consanguinity and Wahlund effect in natural populations of those three economically important cyst nematodes using microsatellite markers: Globodera pallida, G. tabacum and Heterodera schachtii, pests of potato, tobacco and sugar beet, respectively. The results show a consistent pattern of heterozygote deficiency in the three nematode species sampled at the spatial scale of the host plant. We demonstrate that the prevalence of null alleles is weak and that heterozygote deficits do not have a single origin. Our results suggested that it is restricted dispersal that leads to heterozygote deficits through both consanguinity and substructure, which effects can be linked to soil movement, cyst density, and the number of generations per year. We discuss potential implications for the durability of plant resistances that are used to protect crops against parasites in which mating between relatives occur. While consanguineous mating leads to homozygosity at all loci, including loci governing avirulence/virulence, which favours the expression of virulence when recessive, the Wahlund effect is expected to have no particular effect on the adaptation of nematodes to resistances. © 2015 John Wiley & Sons Ltd.

Effect of mine tailing on the spatial variability of soil nematodes from lead pollution in La Union (Spain).

PubMed

Rodríguez Martín, José Antonio; Gutiérrez, Carmen; Escuer, Miguel; García-González, Ma Teresa; Campos-Herrera, Raquel; Aguila, Nancy

2014-03-01

The Cartagena-La Union mining district, exploited since the end of the 3rd century BC, was one of the world's largest lead producers in the 19th century. Although activity ceased in 1991, today mining residues pose a huge pollution problem. This study characterises lead contents (total and DPTA) and other soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.) using multivariate geostatistical methods in relation to nematode diversity. In this work, trophic groups and metabolic footprints of soil nematodes were measured using 193 samples from the mining, natural and agricultural areas in this district. We explored the relationship between soil health and nematode communities. High lead concentrations were quantified: mean 8,500 mg kg(-1) for total and 340 mg kg(-1) for DPTA in this mining area. Although nematode diversity was broad (81 taxa), their diversity, abundance and metabolic footprints significantly reduced in the mining area. Significant differences in the nematode community structure were observed, and the relative abundance of predators was sensitive to mine and agricultural activities, whilst omnivores reduced only in the agricultural area, and bacterial feeders exhibited a differential response to both anthropogenic disturbances. The total abundance of nematodes, trophic groups and c-p groups correlated negatively with soil Pb contents, and a positive relationship was found with SOM and N, P and K contents. Copyright © 2013 Elsevier B.V. All rights reserved.

Microsporidia-nematode associations in methane seeps reveal basal fungal parasitism in the deep sea

PubMed Central

Sapir, Amir; Dillman, Adler R.; Connon, Stephanie A.; Grupe, Benjamin M.; Ingels, Jeroen; Mundo-Ocampo, Manuel; Levin, Lisa A.; Baldwin, James G.; Orphan, Victoria J.; Sternberg, Paul W.

2013-01-01

The deep sea is Earth's largest habitat but little is known about the nature of deep-sea parasitism. In contrast to a few characterized cases of bacterial and protistan parasites, the existence and biological significance of deep-sea parasitic fungi is yet to be understood. Here we report the discovery of a fungus-related parasitic microsporidium, Nematocenator marisprofundi n. gen. n. sp. that infects benthic nematodes at methane seeps on the Pacific Ocean floor. This infection is species-specific and has been temporally and spatially stable over 2 years of sampling, indicating an ecologically consistent host-parasite interaction. A high distribution of spores in the reproductive tracts of infected males and females and their absence from host nematodes' intestines suggests a sexual transmission strategy in contrast to the fecal-oral transmission of most microsporidia. N. marisprofundi targets the host's body wall muscles causing cell lysis, and in severe infection even muscle filament degradation. Phylogenetic analyses placed N. marisprofundi in a novel and basal clade not closely related to any described microsporidia clade, suggesting either that microsporidia-nematode parasitism occurred early in microsporidia evolution or that host specialization occurred late in an ancient deep-sea microsporidian lineage. Our findings reveal that methane seeps support complex ecosystems involving interkingdom interactions between bacteria, nematodes, and parasitic fungi and that microsporidia parasitism exists also in the deep-sea biosphere. PMID:24575084

The complete mitochondrial genomes of three parasitic nematodes of birds: a unique gene order and insights into nematode phylogeny

PubMed Central

2013-01-01

Background Analyses of mitochondrial (mt) genome sequences in recent years challenge the current working hypothesis of Nematoda phylogeny proposed from morphology, ecology and nuclear small subunit rRNA gene sequences, and raise the need to sequence additional mt genomes for a broad range of nematode lineages. Results We sequenced the complete mt genomes of three Ascaridia species (family Ascaridiidae) that infest chickens, pigeons and parrots, respectively. These three Ascaridia species have an identical arrangement of mt genes to each other but differ substantially from other nematodes. Phylogenetic analyses of the mt genome sequences of the Ascaridia species, together with 62 other nematode species, support the monophylies of seven high-level taxa of the phylum Nematoda: 1) the subclass Dorylaimia; 2) the orders Rhabditida, Trichinellida and Mermithida; 3) the suborder Rhabditina; and 4) the infraorders Spiruromorpha and Oxyuridomorpha. Analyses of mt genome sequences, however, reject the monophylies of the suborders Spirurina and Tylenchina, and the infraorders Rhabditomorpha, Panagrolaimomorpha and Tylenchomorpha. Monophyly of the infraorder Ascaridomorpha varies depending on the methods of phylogenetic analysis. The Ascaridomorpha was more closely related to the infraorders Rhabditomorpha and Diplogasteromorpha (suborder Rhabditina) than they were to the other two infraorders of the Spirurina: Oxyuridorpha and Spiruromorpha. The closer relationship among Ascaridomorpha, Rhabditomorpha and Diplogasteromorpha was also supported by a shared common pattern of mitochondrial gene arrangement. Conclusions Analyses of mitochondrial genome sequences and gene arrangement has provided novel insights into the phylogenetic relationships among several major lineages of nematodes. Many lineages of nematodes, however, are underrepresented or not represented in these analyses. Expanding taxon sampling is necessary for future phylogenetic studies of nematodes with mt genome

7 CFR 301.85-9 - Movement of live golden nematodes.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 5 2013-01-01 2013-01-01 false Movement of live golden nematodes. 301.85-9 Section... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Golden Nematode Quarantine and Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise...

7 CFR 301.85-9 - Movement of live golden nematodes.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 5 2012-01-01 2012-01-01 false Movement of live golden nematodes. 301.85-9 Section... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Golden Nematode Quarantine and Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise...

7 CFR 301.85-9 - Movement of live golden nematodes.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 5 2014-01-01 2014-01-01 false Movement of live golden nematodes. 301.85-9 Section... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Golden Nematode Quarantine and Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise...

7 CFR 301.85-9 - Movement of live golden nematodes.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 5 2011-01-01 2011-01-01 false Movement of live golden nematodes. 301.85-9 Section... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Golden Nematode Quarantine and Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise...

Nematode CLE signaling in Arabidopsis requires CLAVATA2 and CORYNE

USDA-ARS?s Scientific Manuscript database

Plant-parasitic cyst nematodes secrete CLAVATA3 (CLV3)/ESR(CLE)-like effector proteins. These proteins have been shown to act as ligand mimics of plant CLE peptides and are required for successful nematode infection; however, the receptors for nematode CLE-like peptides have not been identified. Her...

Bacterial microbiome and nematode occurrence in different potato agricultural soils

USDA-ARS?s Scientific Manuscript database

Pratylenchus neglectus and Meloidogyne chitwoodi are the main plant-parasitic nematodes in potato crops of the San Luis Valley, Colorado. Bacterial microbiome (16S rRNA copies per gram of soil) and nematode communities (nematodes per 200 gr of soil) from five different potato farms were analyzed to ...

Efficacy of an energy block containing Duddingtonia flagrans in the control of gastrointestinal nematodes of sheep.

PubMed

Sagüés, María F; Fusé, Luis A; Fernández, Alicia S; Iglesias, Lucía E; Moreno, Fabiana C; Saumell, Carlos A

2011-09-01

The efficacy of the nematode-trapping fungus Duddingtonia flagrans incorporated into an energy block was evaluated for the control of gastrointestinal nematodes in sheep. Four naturally parasitised sheep with average nematode egg counts of 2,470 eggs per gram grazed by pairs on two similar parasite-free paddocks for 30 days. During that period, one pair of sheep (treated animals, T1) received an energy block containing chlamydospores of D. flagrans at a dose of 200,000 chlamydopores/kg bw/day, while the second pair (control animals, C1) received a fungus-free energy block. The animals in both groups were taken off the paddocks after contaminating the pastures for a month with either nematode eggs plus fungal chlamydospores (T1) or nematode eggs alone (C1). Twelve parasite-free sheep were divided into two groups of six animals each, the treated group (T2) was placed on the paddock previously contaminated with parasites and fungus, while the control group (C2) was placed on the parasite-only paddock. These two groups grazed on their respective paddocks during 30 days and were then housed for 15 days, after which period they were slaughtered in order to determine the parasite burden present in each animal. Results showed that animals in group T2 harboured significantly less nematodes than their counterpart in group C2. The efficacy of D. flagrans was 92% against the total parasite burden, 100% against Haemonchus contortus and Teladorsagia circumcincta, 89.9% against Trichostrongylus colubriformis, 87.5% against Cooperia onchopora, and 90% against Trichostrongylus axei. No efficacy was detected against Nematodirus spathiger, Trichuris ovis and T. skrjabini.

Diatom feeding across trophic guilds in tidal flat nematodes, and the importance of diatom cell size

NASA Astrophysics Data System (ADS)

Moens, Tom; Vafeiadou, Anna-Maria; De Geyter, Ellen; Vanormelingen, Pieter; Sabbe, Koen; De Troch, Marleen

2014-09-01

We examine the capacity of nematodes from three feeding types (deposit feeder, epistrate feeder, predator) to utilize microphytobenthos (MPB), and assess whether diatom cell size and consumer body size are important drivers of their feeding. We analyzed natural stable isotope ratios of carbon and nitrogen in abundant nematode genera and a variety of carbon sources at an estuarine intertidal flat. All nematodes had δ13C indicating that MPB is their major carbon source. δ15N, however, demonstrated that only one deposit and one epistrate feeder genus obtained most of their carbon from direct grazing on MPB, whereas other deposit feeders and predators obtained at least part of their carbon by predation on MPB grazers. We then performed a microcosm experiment in which equal cell numbers of each of three differently sized strains of the pennate diatom Seminavis were offered as food to four, one and one genera of deposit feeders, epistrate feeders and predators, respectively. Previous studies have shown that all but the epistrate feeder ingest whole diatoms, whereas the epistrate feeder pierces cells and sucks out their contents. Most genera showed markedly higher carbon absorption from medium and large cells than from small ones. When considering the number of cells consumed, however, none of the nematodes which ingest whole cells exhibited a clear preference for any specific diatom size. The epistrate feeder was the smallest nematode taxon considered here, yet it showed a marked preference for large cells. These results highlight that the feeding mechanism is much more important than consumer size as a driver of particle size selection in nematodes grazing MPB.

Ecology of the Pinewood Nematode in Southern Pine Chip Piles

Treesearch

L. David Dwinell

1986-01-01

The optimum temperature range for pinewood nematodes in southern pine chips was 35 to 40° C. Nematode populations declined at temperatures of -20°C. at temperatures above 45°C. and in anaerobic environments. Wood moisture content and presence of bluestain fungus also influenced nematode populations.

Novel RNA viruses within plant parasitic cyst nematodes

PubMed Central

Ruark, Casey L.; Gardner, Michael; Mitchum, Melissa G.; Davis, Eric L.

2018-01-01

The study of invertebrate–and particularly nematode–viruses is emerging with the advancement of transcriptome sequencing. Five single-stranded RNA viruses have now been confirmed within the economically important soybean cyst nematode (SCN; Heterodera glycines). From previous research, we know these viruses to be widespread in greenhouse and field populations of SCN. Several of the SCN viruses were also confirmed within clover (H. trifolii) and beet (H. schachtii) cyst nematodes. In the presented study, we sequenced the transcriptomes of several inbred SCN populations and identified two previously undiscovered viral-like genomes. Both of these proposed viruses are negative-sense RNA viruses and have been named SCN nyami-like virus (NLV) and SCN bunya-like virus (BLV). Finally, we analyzed publicly available transcriptome data of two potato cyst nematode (PCN) species, Globodera pallida and G. rostochiensis. From these data, a third potential virus was discovered and called PCN picorna-like virus (PLV). PCN PLV is a positive-sense RNA virus, and to the best of our knowledge, is the first virus described within PCN. The presence of these novel viruses was confirmed via qRT-PCR, endpoint PCR, and Sanger sequencing with the exception of PCN PLV due to quarantine restrictions on the nematode host. While much work needs to be done to understand the biological and evolutionary significance of these viruses, they offer insight into nematode ecology and the possibility of novel nematode management strategies. PMID:29509804

Nematodes as Sentinels of Heavy Metals and Organic Toxicants in the Soil

PubMed Central

Ekschmitt, Klemens; Korthals, Gerard W.

2006-01-01

Field and laboratory research has repeatedly shown that free-living soil nematodes differ in their sensitivity to soil pollution. In this paper, we analyze whether nematode genera proved sensitive or tolerant toward heavy metals and organic pollutants in six long-term field experiments. We discuss overlaps between nematode physiological responses to heavy metals and to organic pollutants, which may explain why nematodes can exhibit co-tolerance toward several contaminants. We propose a simple method for separating direct effects of soil contamination on nematode populations from indirect effects mediated through the food chain. Finally, we analyze the extent to which nematodes exhibited consistent responses across the experiments analyzed. Our results show that (a) indirect effects of pollution were generally strong; (b) fewer nematode genera were tolerant than sensitive; (c) many genera, including practically all Adenophorea, exhibited a common response pattern to contaminants; and (d) several genera of the Secernentea exhibited differential tolerance toward particular pollutants. We conclude that bioindication of soil contamination should preferentially be based on tolerant, and less on sensitive, nematodes. We provide a list of nematode genera that may potentially serve as differential bioindicators for specific soil contaminants. PMID:19259425

CD4+ T Cell Response Correlates with Naturally Acquired Antibodies against Plasmodium vivax Tryptophan-Rich Antigens

PubMed Central

Zeeshan, Mohammad; Tyagi, Kriti

2015-01-01

Tryptophan-rich proteins play important biological functions for the Plasmodium parasite. Plasmodium vivax contains remarkably large numbers of such proteins belonging to the “Pv-fam-a” family that need to be characterized. Earlier, we reported the presence of memory T cells and naturally acquired antibodies against 15 of these proteins in P. vivax malaria-exposed individuals (M. Zeeshan, H. Bora, and Y. D. Sharma, J Infect Dis 207:175–185, 2013, http://dx.doi.org/10.1093/infdis/jis650). Here, we sought to characterize and ascertain the cross talk between effector responses of T and B cells in malarial patients against all Pv-fam-a family proteins. Therefore, we expressed the remaining 21 of these proteins in Escherichia coli and studied the humoral and cellular immune responses based on the same parameters used in our previous study. Naturally acquired IgG antibodies were detected against all 21 antigens in P. vivax patient sera (37.7 to 94.4% seropositivity). These antigens were able to activate the lymphocytes of P. vivax-exposed individuals, and the activated CD4+ T lymphocytes produced higher levels of Th1 (interleukin-2 [IL-2] and gamma interferon [IFN-γ]) and Th2 (IL-4 and IL-10) cytokines than the healthy controls, but the response was Th2 biased. The combined results of present and previous studies seem to suggest a striking link between induction of the CD4+ T cell response and naturally acquired antibodies against all 36 proteins of the Pv-fam-a family, the majority of them having conserved sequences in the parasite population. Further work is required to utilize this information to develop immunotherapeutic treatments for this disease. PMID:25733522

An analysis of using entomopathogenic nematodes against above-ground pests.

PubMed

Arthurs, S; Heinz, K M; Prasifka, J R

2004-08-01

Applications of entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae have traditionally been targeted against soil insects. Nonetheless, research over the last two decades highlights the potential of such agents against above-ground pests under certain circumstances. A general linear model was used to test for patterns in efficacy among 136 published trials with Steinernema carpocapsae Weiser, the most common species applied against foliar and other above-ground pests. The focus was on field and greenhouse assessments, rather than laboratory assays where relevant ecological barriers to infection are typically removed. The model showed differences in nematode treatment efficacy depending on the pests' target habitat (bore holes > cryptic foliage > exposed foliage) and trial location (greenhouse > field studies). Relative humidity and temperature during and up to 8 h post-application were also predicted to influence rates of nematode infection obtained. Conversely, spray adjuvants (both wetting agents and anti-desiccants) and nematode dosage applied (both concentration and use of consecutive applications 3-4 days apart) did not explain a significant amount of variance in nematode performance. With reference to case studies the model is used to discuss the relative importance of different factors on nematode efficacy and highlight priorities for workers considering using entomopathogenic nematodes to target pests in novel environments.

7 CFR 301.85-9 - Movement of live golden nematodes.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Movement of live golden nematodes. 301.85-9 Section... Regulations § 301.85-9 Movement of live golden nematodes. Regulations requiring a permit for and otherwise governing the movement of live golden nematodes in interstate or foreign commerce are contained in the...

Nematode parasites of waterfowl (Anseriformes) from western United States

USGS Publications Warehouse

McDonald, M.E.

1974-01-01

Thirty-four species of nematodes were found in 415 Anseriformes (Anatidae) of 27 species; 93.7% of birds over 4 weeks old were infected. Data on prevalence, host specificity, age of host, and geographic distribution are given. Infections were more intense in sick birds and birds in poor physical condition. Accidental or abnormal infection was more likely in sick than in normal birds. From 1 to 13 species of nematodes are reported from each host species, including 118 new host records, 3 nematodes new for North America, and 1 new species. Multiple infections were present in 76.5% of birds parasitized; eight species of nematodes were found in one whistling swan (Olor columbianus).

[Screening endophytic bacteria against plant-parasitic nematodes].

PubMed

Peng, Shuang; Yan, Shuzhen; Chen, Shuanglin

2011-03-01

Plant-parasite nematode is one of the most important pathogens in plant. Our objective is to screen endophytic bacteria against plant-parasitic nematodes from plant. Endophytic bacteria were isolated and screened by testing their metabolite against Bursaphelenchus xylophilus in vitro. Those strains inhibiting B. xylophilus were selected to culture in liquid medium and fermentation conditions were optimized by orthogonal test. The stability of the antinematode substances was evaluated by various. In addition, four strains were identified by 16SrDNA sequence analysis. In total 13 strains of endophytic bacteria secreting antinematode metabolite were isolated from 6 species of plant. The supernatant of the fermentation broth of these endophytic bacteria gave 100% mortality of nematodes after treated as the follows: 1 ml each was mixed with 0.2 ml of the suspension of nematodes (2000 nematodes/ml) then incubated at 250C for 24 h, some of which could led to leakage or dissolution of nematodes. Among them, four strains, BCM2, SZ5, CCM7 and DP1, showed stronger activity than others. The supernatants diluted three times also gave not less than 95% mortality after 24 h treatment, and those from DP1 and SZ5 even gave 100% mortality. The fermentation conditions of the four strains were optimized and the antinematode activity grew up four times after optimization. The antinematode substances of these strains were found stable when treated with protease or heating or stored at 4 degrees C after 100 days, while instable when treated with acid or alkali. DP1 and CCM7 were identified to be Bacillus subtilis, while SZ5 and BCM2 to be Bacillus cereus. Endophytic bacteria secreting antinematode metabolite were found in economic crops. The metabolite of some strains showed strong and stable antinematode activity. Our results indicate the real potential of biocontrol by endophytic bacteria.

A case report of inhalation anthrax acquired naturally.

PubMed

Azarkar, Zohreh; Bidaki, Majid Zare

2016-03-03

Anthrax is a zoonotic occupational disease caused by Bacillus anthracis, a rod-shaped immobile aerobic gram-positive bacteria with spore. Anthrax occurs in humans randomly and with low frequency. Most cases of anthrax are acquired through contact with infected animals or contaminated animal products. This old disease became particularly important since 2001 that the biological spores were exploited in America. Depending on the transmission method of the disease, clinical manifestations occur in three classes: Cutaneous, respiratory, and gastrointestinal anthrax. The respiratory form is considered as the most fatal and a rare form of anthrax intending to show complicated and unusual manifestations. In this case report a rare case of inhalation anthrax acquired naturally in southeast of Iran is presented. A blind 65-year-old man, living in a rural area, was admitted with respiratory infection, fever, dyspnea, loss of appetite, and myalgia. The patient was treated with outpatient antibiotics a week ago. After admission, the patient was again treated for pneumonia, but there was no improvement despite treatment and the patient was suffering from septicemia symptoms. Radiographic images showed wide mediastinum. Bacillus anthracis was isolated from blood and sputum culture and the results were confirmed by colony morphology, biochemical reactions and PCR. The treatment was changed to ciprofloxacin, clindamycin, and penicillin. On the second day of anthrax treatment, the patient was complicated with jaundice, elevation of liver enzymes, and a significant drop in hemoglobin, hematocrit, and platelet despite lack of obvious bleeding and was complicated with respiratory distress and sepsis and died a week after treatment. We could discover no specific exposure associated with anthrax infection for this patient. However, due to being located in an endemic and enzootic area, it is proposed that the exposure occurred through contact with infected airborne dust or an unknown

Efficacy against nematode and cestode infections and safety of a novel topical fipronil, (S)-methoprene, eprinomectin and praziquantel combination product in domestic cats under field conditions in Europe.

PubMed

Rehbein, Steffen; Capári, Balazs; Duscher, Georg; Keidane, Dace; Kirkova, Zvezdelina; Petkevičius, Saulius; Rapti, Dhimiter; Wagner, Annegret; Wagner, Thomas; Chester, S Theodore; Rosentel, Joseph; Tielemans, Eric; Visser, Martin; Winter, Renate; Kley, Katrin; Knaus, Martin

2014-04-28

A novel topical combination product (BROADLINE(®), Merial) composed of fipronil, (S)-methoprene, eprinomectin and praziquantel was evaluated for safety and efficacy against nematode and cestode infections in domestic cats. The study comprised a multi-centre, positive control, blinded, field study, using a randomized block design based on order of presentation for allocation. In total 196 client-owned cats, confirmed as positive for naturally acquired infections of nematodes and/or cestodes by pre-treatment faecal examination, were studied in seven countries in Europe. Pre-treatment faecal examination revealed the presence of Toxocara, hookworm, Capillaria and/or spirurid nematode infections in 129, 73, 33 or 1 cat(s), respectively; infections with taeniid and Dipylidium cestodes were demonstrated in 39 and 17 cats, respectively. Cats were allocated randomly to one of two treatments in a ratio of 2, topical fipronil (8.3%, w/v), (S)-methoprene (10%, w/v), eprinomectin (0.4%, w/v) and praziquantel (8.3%, w/v) (BROADLINE(®), Merial; 130 cats); and 1, topical PROFENDER(®) Spot-On (Bayer; 66 cats) and treated once on Day 0. For evaluation of efficacy, two faecal samples were collected, one prior to treatment (Day -4 ± 4 days) and one at the end of the study (Day 14 ± 5 days). These were examined for fecal forms of nematode and cestode parasites. For evaluation of safety, cats were examined by a veterinarian before treatment and at the end of the study, and cat owners recorded the health status of their cats daily until the end of the study. For cats treated with Broadline(®), the efficacy was >99.9%, 100%, and 99.6% for Toxocara, hookworms, and Capillaria, respectively; and the efficacy was >99.9%, >99.9%, and 98.5%, respectively, for the cats treated with Profender(®) (p<0.001 for all nematodes and both treatments). Efficacy was 100% for both cestodes for both treatments (p<0.001). No treatment related adverse experiences were observed throughout the study. For

Control of the peachtree borer using beneficial nematodes

USDA-ARS?s Scientific Manuscript database

The peachtree borer, Synanthedon exitiosa, is a major pest of peaches and other stone fruits. Our research indicates that entomopathogenic nematodes, also known as beneficial nematodes, can be used effectively to control the insect. We conducted replicated experiments in randomized block designs ov...

Book review: Systematics of Cyst Nematodes (Nematoda: Heteroderinae)

USDA-ARS?s Scientific Manuscript database

The cyst nematodes are an important group of plant-parasitic nematodes that cause billions of dollars in economic damage to crops every year. This article reviews a recently published, two-volume monograph that describes the morphological and molecular characteristics of these agriculturally signif...

Infection Assay of Cyst Nematodes on Arabidopsis Roots.

PubMed

Bohlmann, Holger; Wieczorek, Krzysztof

2015-09-20

Plant parasitic nematodes are devastating pests on many crops. Juveniles (J2) of cyst nematodes invade the roots to induce a syncytium. This feeding site is their only source of nutrients. Male nematodes leave the roots after the fourth molt to mate with females. The females stay attached to their syncytia throughout their life and produce hundreds of eggs, which are contained in their bodies. When the females die their bodies form the cysts, which protect the eggs. Cysts can survive for many years in the soil until favorable conditions induce hatching of the juveniles. The beet cyst nematode Heterodera schachtii ( H. schachtii )is a pathogen of sugar beet ( Beta vulgaris ) but can also complete its life cycle on Arabidopsis roots growing on agar plates under sterile conditions. We present here protocols for a stock culture of H. schachtii and an infection assay on agar plates.

Ijuhya vitellina sp. nov., a novel source for chaetoglobosin A, is a destructive parasite of the cereal cyst nematode Heterodera filipjevi

PubMed Central

Stadler, Marc; Richert-Poeggeler, Katja R.; Dababat, Abdelfattah A.; Maier, Wolfgang

2017-01-01

Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae), encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal and nematode

Ijuhya vitellina sp. nov., a novel source for chaetoglobosin A, is a destructive parasite of the cereal cyst nematode Heterodera filipjevi.

PubMed

Ashrafi, Samad; Helaly, Soleiman; Schroers, Hans-Josef; Stadler, Marc; Richert-Poeggeler, Katja R; Dababat, Abdelfattah A; Maier, Wolfgang

2017-01-01

Cyst nematodes are globally important pathogens in agriculture. Their sedentary lifestyle and long-term association with the roots of host plants render cyst nematodes especially good targets for attack by parasitic fungi. In this context fungi were specifically isolated from nematode eggs of the cereal cyst nematode Heterodera filipjevi. Here, Ijuhya vitellina (Ascomycota, Hypocreales, Bionectriaceae), encountered in wheat fields in Turkey, is newly described on the basis of phylogenetic analyses, morphological characters and life-style related inferences. The species destructively parasitises eggs inside cysts of H. filipjevi. The parasitism was reproduced in in vitro studies. Infected eggs were found to harbour microsclerotia produced by I. vitellina that resemble long-term survival structures also known from other ascomycetes. Microsclerotia were also formed by this species in pure cultures obtained from both, solitarily isolated infected eggs obtained from fields and artificially infected eggs. Hyphae penetrating the eggshell colonised the interior of eggs and became transformed into multicellular, chlamydospore-like structures that developed into microsclerotia. When isolated on artificial media, microsclerotia germinated to produce multiple emerging hyphae. The specific nature of morphological structures produced by I. vitellina inside nematode eggs is interpreted as a unique mode of interaction allowing long-term survival of the fungus inside nematode cysts that are known to survive periods of drought or other harsh environmental conditions. Generic classification of the new species is based on molecular phylogenetic inferences using five different gene regions. I. vitellina is the only species of the genus known to parasitise nematodes and produce microsclerotia. Metabolomic analyses revealed that within the Ijuhya species studied here, only I. vitellina produces chaetoglobosin A and its derivate 19-O-acetylchaetoglobosin A. Nematicidal and nematode

Stimulation of the Salicylic Acid Pathway Aboveground Recruits Entomopathogenic Nematodes Belowground

PubMed Central

Filgueiras, Camila Cramer; Willett, Denis S.; Junior, Alcides Moino; Pareja, Martin; Borai, Fahiem El; Dickson, Donald W.; Stelinski, Lukasz L.; Duncan, Larry W.

2016-01-01

Plant defense pathways play a critical role in mediating tritrophic interactions between plants, herbivores, and natural enemies. While the impact of plant defense pathway stimulation on natural enemies has been extensively explored aboveground, belowground ramifications of plant defense pathway stimulation are equally important in regulating subterranean pests and still require more attention. Here we investigate the effect of aboveground stimulation of the salicylic acid pathway through foliar application of the elicitor methyl salicylate on belowground recruitment of the entomopathogenic nematode, Steinernema diaprepesi. Also, we implicate a specific root-derived volatile that attracts S. diaprepesi belowground following aboveground plant stimulation by an elicitor. In four-choice olfactometer assays, citrus plants treated with foliar applications of methyl salicylate recruited S. diaprepesi in the absence of weevil feeding as compared with negative controls. Additionally, analysis of root volatile profiles of citrus plants receiving foliar application of methyl salicylate revealed production of d-limonene, which was absent in negative controls. The entomopathogenic nematode S. diaprepesi was recruited to d-limonene in two-choice olfactometer trials. These results reinforce the critical role of plant defense pathways in mediating tritrophic interactions, suggest a broad role for plant defense pathway signaling belowground, and hint at sophisticated plant responses to pest complexes. PMID:27136916

[Distribution characteristics of soil nematodes in reclaimed land of copper-mine-tailings in different plant associations].

PubMed

Zhu, Yong-heng; Li, Ke-zhong; Zhang, Heng; Han, Fei; Zhou, Ju-hua; Gao, Ting-ting

2015-02-01

A survey was carried out to investigate soil nematode communities in the plant associations of gramineae (Arthraxon lanceolatus, AL; Imperata cylindrica, IC) and leguminosae (Glycine soja, GS) in reclaimed land of copper-mine-tailings and in the plant associations of gramineae (Digitaria chrysoblephara, DC-CK) of peripheral control in Fenghuang Mountain, Tongling City. A total of 1277 nematodes were extracted and sorted into 51 genera. The average individual density of the nematodes was 590 individuals · 100 g(-1) dry soil. In order to analyze the distribution character- istics of soil nematode communities in reclaimed land of copper-mine-tailings, Shannon community diversity index and soil food web structure indices were applied in the research. The results showed that the total number of nematode genus and the Shannon community diversity index of soil nematode in the three plant associations of AL, IC and GS were less than that in the plant associations of DC-CK. Compared with the ecological indices of soil nematode communities among the different plant associations in reclaimed land of copper-mine-tailings and peripheral natural habitat, we found that the structure of soil food web in the plant associations of GS was more mature, with bacterial decomposition being dominant in the soil organic matter decomposition, and that the soil ecosystem in the plant associations of GS was not stable with low interference. This indicated that the soil food web in the plant associations of leguminosae had a greater development potential to improve the ecological stability of the reclaimed land of copper-mine-tailings. On the other hand, the structure of soil food web in the plant associations of AL and IC were relatively stable in a structured state with fungal decomposition being dominant in the decomposition of soil organic matter. This indicated that the soil food web in the plant associations of gramineae was at a poor development level.

Subterranean, herbivore-induced plant volatile increases biological control activity of multiple beneficial nematode species in distinct habitats

USDA-ARS?s Scientific Manuscript database

While the role of herbivore-induced volatiles in plant-herbivore-natural enemy interactions is well documented aboveground, new evidence suggests that belowground volatile emissions can protect plants by attracting entomopathogenic nematodes (EPNs). However, due to methodological limitations, no stu...

Chemical ecology and isolation of biologically active compounds from parasitic nematodes

USDA-ARS?s Scientific Manuscript database

Root knot nematodes (Meloidogyne spp) are possibly the economically most important and best-studied species of plant parasitic nematodes. However, for Meloidogyne spp and the intensely studied nematode, Caenorhabditis elegans, very little is known about signaling within and in-between species. It h...

Interspecific and host-related gene expression patterns in nematode-trapping fungi.

PubMed

Andersson, Karl-Magnus; Kumar, Dharmendra; Bentzer, Johan; Friman, Eva; Ahrén, Dag; Tunlid, Anders

2014-11-11

Nematode-trapping fungi are soil-living fungi that capture and kill nematodes using special hyphal structures called traps. They display a large diversity of trapping mechanisms and differ in their host preferences. To provide insights into the genetic basis for this variation, we compared the transcriptome expressed by three species of nematode-trapping fungi (Arthrobotrys oligospora, Monacrosporium cionopagum and Arthrobotrys dactyloides, which use adhesive nets, adhesive branches or constricting rings, respectively, to trap nematodes) during infection of two different plant-pathogenic nematode hosts (the root knot nematode Meloidogyne hapla and the sugar beet cyst nematode Heterodera schachtii). The divergence in gene expression between the fungi was significantly larger than that related to the nematode species being infected. Transcripts predicted to encode secreted proteins and proteins with unknown function (orphans) were overrepresented among the highly expressed transcripts in all fungi. Genes that were highly expressed in all fungi encoded endopeptidases, such as subtilisins and aspartic proteases; cell-surface proteins containing the carbohydrate-binding domain WSC; stress response proteins; membrane transporters; transcription factors; and transcripts containing the Ricin-B lectin domain. Differentially expressed transcripts among the fungal species encoded various lectins, such as the fungal fruit-body lectin and the D-mannose binding lectin; transcription factors; cell-signaling components; proteins containing a WSC domain; and proteins containing a DUF3129 domain. A small set of transcripts were differentially expressed in infections of different host nematodes, including peptidases, WSC domain proteins, tyrosinases, and small secreted proteins with unknown function. This is the first study on the variation of infection-related gene expression patterns in nematode-trapping fungi infecting different host species. A better understanding of these

Generalists at the interface: Nematode transmission between wild and domestic ungulates.

PubMed

Walker, Josephine G; Morgan, Eric R

2014-12-01

Many parasitic nematode species are generalists capable of infecting multiple host species. The complex life cycle of nematodes, involving partial development outside of the host, facilitates transmission of these parasites between host species even when there is no direct contact between hosts. Infective nematode larvae persist in the environment, and where grazing or water sources are shared ingestion of parasite larvae deposited by different host species is likely. In this paper we examine the extent to which nematode parasite species have been observed in sympatric wild and domestic ungulates. First, using existing host-parasite databases, we describe expected overlap of 412 nematode species between 76 wild and 8 domestic ungulate host species. Our results indicate that host-specific parasites make up less than half of the nematode parasites infecting any particular ungulate host species. For wild host species, between 14% (for common warthog) and 76% (for mouflon) of parasitic nematode species are shared with domestic species. For domestic host species, between 42% (for horse) and 77% (for llamas/alpacas) of parasitic nematode species are shared with wild species. We also present an index of liability to describe the risk of cross-boundary parasites to each host species. We then examine specific examples from the literature in which transmission of nematode parasites between domestic and wild ungulates is described. However, there are many limitations in the existing data due to geographical bias and certain host species being studied more frequently than others. Although we demonstrate that many species of parasitic nematode are found in both wild and domestic hosts, little work has been done to demonstrate whether transmission is occurring between species or whether similar strains circulate separately. Additional research on cross-species transmission, including the use of models and of genetic methods to define strains, will provide evidence to answer this

Generalists at the interface: Nematode transmission between wild and domestic ungulates

PubMed Central

Walker, Josephine G.; Morgan, Eric R.

2014-01-01

Many parasitic nematode species are generalists capable of infecting multiple host species. The complex life cycle of nematodes, involving partial development outside of the host, facilitates transmission of these parasites between host species even when there is no direct contact between hosts. Infective nematode larvae persist in the environment, and where grazing or water sources are shared ingestion of parasite larvae deposited by different host species is likely. In this paper we examine the extent to which nematode parasite species have been observed in sympatric wild and domestic ungulates. First, using existing host–parasite databases, we describe expected overlap of 412 nematode species between 76 wild and 8 domestic ungulate host species. Our results indicate that host-specific parasites make up less than half of the nematode parasites infecting any particular ungulate host species. For wild host species, between 14% (for common warthog) and 76% (for mouflon) of parasitic nematode species are shared with domestic species. For domestic host species, between 42% (for horse) and 77% (for llamas/alpacas) of parasitic nematode species are shared with wild species. We also present an index of liability to describe the risk of cross-boundary parasites to each host species. We then examine specific examples from the literature in which transmission of nematode parasites between domestic and wild ungulates is described. However, there are many limitations in the existing data due to geographical bias and certain host species being studied more frequently than others. Although we demonstrate that many species of parasitic nematode are found in both wild and domestic hosts, little work has been done to demonstrate whether transmission is occurring between species or whether similar strains circulate separately. Additional research on cross-species transmission, including the use of models and of genetic methods to define strains, will provide evidence to answer

Aggregative group behavior in insect parasitic nematode disperal

USDA-ARS?s Scientific Manuscript database

Movement behavior is critical to determination of spatial ecology and success of foraging in predators and parasites. In this study movement behavior of entomopathogenic nematodes was explored. Movement patterns in sand were investigated when nematodes were applied to a specific locus or when the ne...

Nematodes as bioindicators of soil degradation due to heavy metals.

PubMed

Šalamún, Peter; Renčo, Marek; Kucanová, Eva; Brázová, Tímea; Papajová, Ingrid; Miklisová, Dana; Hanzelová, Vladimíra

2012-11-01

The effect of distance from a heavy metal pollution source on the soil nematode community was investigated on four sampling sites along an 4 km transect originating at the Kovohuty a.s. Krompachy (pollution source). The soil nematode communities were exposed to heavy metal influence directly and through soil properties changes. We quantified the relative effects of total and mobile fraction of metals (As, Cd, Cr, Cu, Pb, and Zn) on soil ecosystem using the nematode community structure (trophic and c-p groups,) and ecological indices (Richness of genera, H', MI2-5, etc.). Pollution effects on the community structure of soil free living nematodes was found to be the highest near the pollution source, with relatively low population density and domination of insensitive taxa. A decrease in heavy metals contents along the transect was linked with an increase in complexity of nematode community. The majority of used indices (MI2-5, SI, H') negatively correlated (P < 0.05 or P < 0.01) with heavy metals content and were sensitive to soil ecosystem disturbance. Contamination by heavy metals has negatively affected the soil environment, which resulted in nematode community structure and ecological indices changes. Results showed that the free-living nematodes are useful tools for bioindication of contamination and could be used as an alternative to the common approaches based on chemical methods.

Larval nematodes found in amphibians from northeastern Argentina.

PubMed

González, C E; Hamann, M I

2010-11-01

Five species of amphibians, Leptodactylus podicipinus, Scinax acuminatus, S. nasicus, Rhinella fernandezae and Pseudis paradoxa, were collected in Corrientes province, Argentina and searched for larval nematodes. All larval nematodes were found as cysts in the serous of the stomach of hosts. Were identified one superfamily, Seuratoidea; one genus, Spiroxys (Superfamily Gnathostomatoidea) and one family, Rhabdochonidae (Superfamily Thelazioidea). We present a description and illustrations of these taxa. These nematodes have an indirect life cycle and amphibians are infected by consuming invertebrate, the intermediate hosts. The genus Spiroxys and superfamily Seuratoidea were reported for the first time for Argentinean amphibians.

Field trial assessment of ivermectin pharmacokinetics and efficacy against susceptible and resistant nematode populations in cattle.

PubMed

Canton, Candela; Canton, Lucila; Domínguez, María Paula; Moreno, Laura; Lanusse, Carlos; Alvarez, Luis; Ceballos, Laura

2018-05-30

The study compared the pharmacokinetic (PK) behaviour and anthelmintic efficacy against susceptible and resistant nematodes following subcutaneous (SC) and oral administration of ivermectin (IVM) to cattle. Six commercial farms were involved: Farms 1 and 2 (IVM-susceptible nematode population) and Farms 3, 4, 5 and 6 (IVM-resistant nematode population). On each farm, forty-five calves naturally infected with gastrointestinal (GI) nematodes were randomly allocated into three groups (n = 15): untreated control, IVM SC administration, and IVM oral administration (both at 0.2 mg/kg). PK assessment (plasma and faeces) was performed on Farm 1. Efficacy was determined by Faecal Egg Count Reduction Test. IVM systemic availability upon SC administration (421 ± 70.3 ng·d/mL) was higher (P < 0.05) compared to the oral treatment (132 ± 31.3 ng·d/mL). However, higher (P < 0.05) faecal IVM concentrations were observed following oral treatment (9896 ± 1931 ng·d/mL) compared to SC administration (4760 ± 924 ng·d/mL). Similar (91-93%) IVM efficacy was observed on Farms 1 and 2 by both routes. Efficacy against resistant nematodes was slightly higher on Farms 3 and 4 after the oral (63 and 82%, respectively) compared to the SC (36 and 68%, respectively) treatment. However, there was complete therapeutic failure (0% efficacy) on Farm 5 and a very low response on Farm 6 (40 and 41% for SC and oral administration, respectively). Although larger faecal concentrations following IVM oral administration may increase drug exposure of GI adult worms, this does not always improve efficacy against resistant nematodes. The potential therapeutic advantages of oral treatments should be cautiously assessed, especially in presence of anthelmintic resistance. Copyright © 2018 Elsevier B.V. All rights reserved.

Remote Sensing of Parasitic Nematodes in Plants

NASA Technical Reports Server (NTRS)

Lawrence, Gary W.; King, Roger; Kelley, Amber T.; Vickery, John

2007-01-01

A method and apparatus for remote sensing of parasitic nematodes in plants, now undergoing development, is based on measurement of visible and infrared spectral reflectances of fields where the plants are growing. Initial development efforts have been concentrated on detecting reniform nematodes (Rotylenchulus reniformis) in cotton plants, because of the economic importance of cotton crops. The apparatus includes a hand-held spectroradiometer. The readings taken by the radiometer are processed to extract spectral reflectances at sixteen wavelengths between 451 and 949 nm that, taken together, have been found to be indicative of the presence of Rotylenchulus reniformis. The intensities of the spectral reflectances are used to estimate the population density of the nematodes in an area from which readings were taken.

First report of the spiral nematode Helicotylenchus microlobus infecting soybean in North Dakota

USDA-ARS?s Scientific Manuscript database

Spiral nematodes (Helicotylenchus spp.) are common plant-parasitic nematodes in fields of many crops. In June 2015, two soil samples were collected from a soybean field in Richland County, ND. Nematodes were extracted from soil using the sugar centrifugal flotation method. Plant-parasitic nematodes ...

RNA Interference: A Novel Source of Resistance to Combat Plant Parasitic Nematodes.

PubMed

Banerjee, Sagar; Banerjee, Anamika; Gill, Sarvajeet S; Gupta, Om P; Dahuja, Anil; Jain, Pradeep K; Sirohi, Anil

2017-01-01

Plant parasitic nematodes cause severe damage and yield loss in major crops all over the world. Available control strategies include use of insecticides/nematicides but these have proved detrimental to the environment, while other strategies like crop rotation and resistant cultivars have serious limitations. This scenario provides an opportunity for the utilization of technological advances like RNA interference (RNAi) to engineer resistance against these devastating parasites. First demonstrated in the model free living nematode, Caenorhabtidis elegans ; the phenomenon of RNAi has been successfully used to suppress essential genes of plant parasitic nematodes involved in parasitism, nematode development and mRNA metabolism. Synthetic neurotransmitants mixed with dsRNA solutions are used for in vitro RNAi in plant parasitic nematodes with significant success. However, host delivered in planta RNAi has proved to be a pioneering phenomenon to deliver dsRNAs to feeding nematodes and silence the target genes to achieve resistance. Highly enriched genomic databases are exploited to limit off target effects and ensure sequence specific silencing. Technological advances like gene stacking and use of nematode inducible and tissue specific promoters can further enhance the utility of RNAi based transgenics against plant parasitic nematodes.

A Look into Students' Retention of Acquired Nature of Science Understandings

NASA Astrophysics Data System (ADS)

Khishfe, Rola

2015-07-01

Having the learning and retention of science content and skills as a goal of scientific literacy, it is significant to study the issue of retention as it relates to teaching and learning about nature of science (NOS). Then, the purpose of this study was to investigate the development of NOS understandings of students, and the retention of these understandings four months after being acquired through explicit reflective instruction in relation to two contexts. Participants were 24 tenth-grade students at a private high school in a city in the Middle East. Explicit NOS instruction was addressed within a six-week unit about genetic engineering. Three NOS aspects were integrated and dispersed across the unit. A questionnaire, together with semi-structured interviews, was administered as pre-, post-, and delayed post-test to assess the retention of participants' NOS understandings. The questionnaire had two open-ended scenarios addressing controversial socioscientific issues about genetically modified food and water fluoridation. Results showed that most students improved their naïve understandings of NOS in relation to the two contexts following the six-week unit with the explicit NOS instruction. However, these newly acquired NOS understandings were not retained by all students four months after instruction. Many of the students reverted back to their earlier naïve understandings. Conclusions about the factors facilitating the process of retention as the orientation to meaningful learning and the prolonged exposure to the domain were discussed in relation to practical implications in the classroom.

Rhizosphere Colonization and Control of Meloidogyne spp. by Nematode-trapping Fungi

PubMed Central

Persson, Christina; Jansson, Hans-Börje

1999-01-01

The ability of nematode-trapping fungi to colonize the rhizosphere of crop plants has been suggested to be an important factor in biological control of root-infecting nematodes. In this study, rhizosphere colonization was evaluated for 38 isolates of nematode-trapping fungi representing 11 species. In an initial screen, Arthrobotrys dactyloides, A. superba, and Monacrosporium ellipsosporum were most frequently detected in the tomato rhizosphere. In subsequent pot experiments these fungi and the non-root colonizing M. geophyropagum were introduced to soil in a sodium alginate matrix, and further tested both for establishment in the tomato rhizosphere and suppression of root-knot nematodes. The knob-forming M. ellipsosporum showed a high capacity to colonize the rhizosphere both in the initial screen and the pot experiments, with more than twice as many fungal propagules in the rhizosphere as in the root-free soil. However, neither this fungus nor the other nematode-trapping fungi tested reduced nematode damage to tomato plants. PMID:19270886

Human gastrointestinal nematode infections: are new control methods required?

PubMed Central

Stepek, Gillian; Buttle, David J; Duce, Ian R; Behnke, Jerzy M

2006-01-01

Gastrointestinal (GI) nematode infections affect 50% of the human population worldwide, and cause great morbidity as well as hundreds of thousands of deaths. Despite modern medical practices, the proportion of the population infected with GI nematodes is not falling. This is due to a number of factors, the most important being the lack of good healthcare, sanitation and health education in many developing countries. A relatively new problem is the development of resistance to the small number of drugs available to treat GI nematode infections. Here we review the most important parasitic GI nematodes and the methods available to control them. In addition, we discuss the current status of new anthelmintic treatments, particularly the plant cysteine proteinases from various sources of latex-bearing plants and fruits. PMID:16965561

The expression of a naturally occuriing truncated allele of an alpha-SNAP gene suppresses plant parasitic nematode infection

USDA-ARS?s Scientific Manuscript database

rhg1, defined within a 67 kb region of DNA on chromosome 18, is a major quantitative trait locus (QTL) in Glycine max (soybean) providing defense to the soybean cyst nematode (Heterodera glycines). Transcriptional mapping experiments identified an alpha soluble NSF attachment protein (alpha-SNAP) wi...

Functional characterisation of a cyst nematode acetylcholinesterase gene using Caenorhabditis elegans as a heterologous system.

PubMed

Costa, Joana C; Lilley, Catherine J; Atkinson, Howard J; Urwin, Peter E

2009-06-01

Migration of plant-parasitic nematode infective larval stages through soil and invasion of roots requires perception and integration of sensory cues culminating in particular responses that lead to root penetration and parasite establishment. Components of the chemoreceptive neuronal circuitry involved in these responses are targets for control measures aimed at preventing infection. Here we report, to our knowledge, the first isolation of cyst nematode ace-2 genes encoding acetylcholinesterase (AChE). The ace-2 genes from Globodera pallida (Gp-ace-2) and Heterodera glycines (Hg-ace-2) show homology to ace-2 of Caenorhabditis elegans (Ce-ace-2). Gp-ace-2 is expressed most highly in the infective J2 stage with lowest expression in the early parasitic stages. Expression and functional analysis of the Globodera gene were carried out using the free-living nematode C. elegans in order to overcome the refractory nature of the obligate parasite G. pallida to many biological studies. Caenorhabditis elegans transformed with a GFP reporter construct under the control of the Gp-ace-2 promoter exhibited specific and restricted GFP expression in neuronal cells in the head ganglia. Gp-ACE-2 protein can functionally complement its C. elegans homologue. A chimeric construct containing the Ce-ace-2 promoter region and the Gp-ace-2 coding region and 3' untranslated region was able to restore a normal phenotype to the uncoordinated C. elegans double mutant ace-1;ace-2. This study demonstrates conservation of AChE function and expression between free-living and plant-parasitic nematode species, and highlights the utility of C. elegans as a heterologous system to study neuronal aspects of plant-parasitic nematode biology.

Soybean lines evaluated for resistance to reniform nematode

USDA-ARS?s Scientific Manuscript database

Seventy-four wild and domestic soybean (Glycine max and G. soja) lines were evaluated for resistance to reniform nematode (Rotylenchulus reniformis) in growth chamber tests with a day length of 16 hours and temperature held constant at 28 C. Several entries for which reactions to reniform nematode w...

Native nematodes as new bio-insecticides for cranberries

USDA-ARS?s Scientific Manuscript database

In the summer of 2015, an effort was made in central Wisconsin to find an entomopathogenic nematode capable controlling Wisconsin’s cranberry pests. Using a standard baiting method, a nematode of the Oscheius genus was collected from the mossy, sandy, peat-filled soils of a wild cranberry marsh. Thi...

Characterization of reniform nematode genome through shotgun sequencing

USDA-ARS?s Scientific Manuscript database

The reniform nematode (RN), a major agricultural pest particularly on cotton in the United States(U.S.), is among the major plant parasitic nematodes for which limited genomic information exists. In this study, over 380 Mb of sequence data were generated from four pooled adult female RN and assembl...

In-vitro predatory activity of nematophagous fungi from Costa Rica with potential use for controlling sheep and goat parasitic nematodes.

PubMed

Soto-Barrientos, Natalia; de Oliveira, Jaqueline; Vega-Obando, Rommel; Montero-Caballero, Danilo; Vargas, Bernardo; Hernández-Gamboa, Jorge; Orozco-Solano, Claudio

2011-03-01

In tropical and subtropical regions of the world, parasitic diseases are a main cause of losses in livestock productivity. The increased acquired resistence to anthelmintics by gastrointestinal nematodes, requires biological control be considered as a potential feasible and effective alternative. The most effective natural soil enemies of nematodes are nematophagous fungi. In order to collect and identify predator nematophagous fungi (PNF), samples were obtained from 51 farms distributed throughout the seven provinces of Costa Rica. The origin samples included: soil from different crops (potatoes, tomatoes, bananas, ornamental plants, squash and coffee); animal feces (cattle, sheep, goat and horse); soil and fallen leaves from forest; and plants with signs of nematode infection. Each sample was processed using three techniques for the extraction of fungi from soil: sprinkling technique, soil dilution and humidity chamber. Twenty four strains of nematophagous fungi were found in 19 farms; 83.3% of the fungi were isolated by sprinkling technique. The following fungi were identified: Arthrobotrys oligospora (n = 13); Candelabrella musiformis (n = 9); and for the first time there was isolation of A. conoides (n = 1) and A. dactyloides (n = 1) in the country. Moreover, 16 strains from Trichoderma (n=13), Beauveria (n = 1), Clonostachys (n = 1) and Lecanicillium (n = 1) were obtained. In addition, pH of each possible fungal isolation source was measured, and it varied from 5.2 to 9.9, however PNF isolates fell within the range of 5.6 to 7.5. The PNF strains were cultivated in four different media for the production of chhlamydospores: potato dextrose agar (PDA); corn meal agar (CMA); malt extract agar (MEA) and potato carrot agar (PCA). Out of these cultures, 95.8% of the strains formed chlamydospores primarily in the PCA. Of these strains, the profilic spore producers were subjected to ruminant artificial gastrointestinal conditions. A total of 14 fungi were tested, out

Knockdown of HMGB1 in tumor cells attenuates their ability to induce regulatory T cells and uncovers naturally acquired CD8 T cell-dependent antitumor immunity.

PubMed

Liu, Zuqiang; Falo, Louis D; You, Zhaoyang

2011-07-01

Although high mobility group box 1 (HMGB1) in tumor cells is involved in many aspects of tumor progression, its role in tumor immune suppression remains elusive. Host cell-derived IL-10 suppressed a naturally acquired CD8 T cell-dependent antitumor response. The suppressive activity of tumor-associated Foxp3(+)CD4(+)CD25(+) regulatory T cells (Treg) was IL-10 dependent. Neutralizing HMGB1 impaired tumor cell-promoted IL-10 production by Treg. Short hairpin RNA-mediated knockdown of HMGB1 (HMGB1 KD) in tumor cells did not affect tumor cell growth but uncovered naturally acquired long-lasting tumor-specific IFN-γ- or TNF-α-producing CD8 T cell responses and attenuated their ability to induce Treg, leading to naturally acquired CD8 T cell- or IFN-γ-dependent tumor rejection. The data suggest that tumor cell-derived HMGB1 may suppress naturally acquired CD8 T cell-dependent antitumor immunity via enhancing Treg to produce IL-10, which is necessary for Treg-mediated immune suppression.

RNAseq Analysis of the Drosophila Response to the Entomopathogenic Nematode Steinernema

PubMed Central

Yadav, Shruti; Daugherty, Sean; Shetty, Amol Carl; Eleftherianos, Ioannis

2017-01-01

Drosophila melanogaster is an outstanding model to study the molecular and functional basis of host–pathogen interactions. Currently, our knowledge of microbial infections in D. melanogaster is well understood; however, the response of flies to nematode infections is still in its infancy. Here, we have used the potent parasitic nematode Steinernema carpocapsae, which lives in mutualism with its endosymbiotic bacteria Xenorhabdus nematophila, to examine the transcriptomic basis of the interaction between D. melanogaster and entomopathogenic nematodes. We have employed next-generation RNA sequencing (RNAseq) to investigate the transcriptomic profile of D. melanogaster larvae in response to infection by S. carpocapsae symbiotic (carrying X. nematophila) or axenic (lacking X. nematophila) nematodes. Bioinformatic analyses have identified the strong induction of genes that are associated with the peritrophic membrane and the stress response, as well as several genes that participate in developmental processes. We have also found that genes with different biological functions are enriched in D. melanogaster larvae responding to either symbiotic or axenic nematodes. We further show that while symbiotic nematode infection enriched certain known immune-related genes, axenic nematode infection enriched several genes associated with chitin binding, lipid metabolic functions, and neuroactive ligand receptors. In addition, we have identified genes with a potential role in nematode recognition and genes with potential antinematode activity. Findings from this study will undoubtedly set the stage for the identification of key regulators of antinematode immune mechanisms in D. melanogaster, as well as in other insects of socioeconomic importance. PMID:28450373

The Ditylenchus destructor genome provides new insights into the evolution of plant parasitic nematodes

PubMed Central

Zheng, Jinshui; Peng, Donghai; Chen, Ling; Liu, Hualin; Chen, Feng; Xu, Mengci; Ju, Shouyong; Ruan, Lifang

2016-01-01

Plant-parasitic nematodes were found in 4 of the 12 clades of phylum Nematoda. These nematodes in different clades may have originated independently from their free-living fungivorous ancestors. However, the exact evolutionary process of these parasites is unclear. Here, we sequenced the genome sequence of a migratory plant nematode, Ditylenchus destructor. We performed comparative genomics among the free-living nematode, Caenorhabditis elegans and all the plant nematodes with genome sequences available. We found that, compared with C. elegans, the core developmental control processes underwent heavy reduction, though most signal transduction pathways were conserved. We also found D. destructor contained more homologies of the key genes in the above processes than the other plant nematodes. We suggest that Ditylenchus spp. may be an intermediate evolutionary history stage from free-living nematodes that feed on fungi to obligate plant-parasitic nematodes. Based on the facts that D. destructor can feed on fungi and has a relatively short life cycle, and that it has similar features to both C. elegans and sedentary plant-parasitic nematodes from clade 12, we propose it as a new model to study the biology, biocontrol of plant nematodes and the interaction between nematodes and plants. PMID:27466450

The Ditylenchus destructor genome provides new insights into the evolution of plant parasitic nematodes.

PubMed

Zheng, Jinshui; Peng, Donghai; Chen, Ling; Liu, Hualin; Chen, Feng; Xu, Mengci; Ju, Shouyong; Ruan, Lifang; Sun, Ming

2016-07-27

Plant-parasitic nematodes were found in 4 of the 12 clades of phylum Nematoda. These nematodes in different clades may have originated independently from their free-living fungivorous ancestors. However, the exact evolutionary process of these parasites is unclear. Here, we sequenced the genome sequence of a migratory plant nematode, Ditylenchus destructor We performed comparative genomics among the free-living nematode, Caenorhabditis elegans and all the plant nematodes with genome sequences available. We found that, compared with C. elegans, the core developmental control processes underwent heavy reduction, though most signal transduction pathways were conserved. We also found D. destructor contained more homologies of the key genes in the above processes than the other plant nematodes. We suggest that Ditylenchus spp. may be an intermediate evolutionary history stage from free-living nematodes that feed on fungi to obligate plant-parasitic nematodes. Based on the facts that D. destructor can feed on fungi and has a relatively short life cycle, and that it has similar features to both C. elegans and sedentary plant-parasitic nematodes from clade 12, we propose it as a new model to study the biology, biocontrol of plant nematodes and the interaction between nematodes and plants. © 2016 The Author(s).

Sandy beaches: state of the art of nematode ecology.

PubMed

Maria, Tatiana F; Vanaverbeke, Jan; Vanreusel, Ann; Esteves, André M

2016-01-01

In this review, we summarize existing knowledge of the ecology of sandy-beach nematodes, in relation to spatial distribution, food webs, pollution and climate change. We attempt to discuss spatial scale patterns (macro-, meso- and microscale) according to their degree of importance in structuring sandy-beach nematode assemblages. This review will provide a substantial background on current knowledge of sandy-beach nematodes, and can be used as a starting point to delineate further investigations in this field. Over decades, sandy beaches have been the scene of studies focusing on community and population ecology, both related to morphodynamic models. The combination of physical factors (e.g. grain size, tidal exposure) and biological interactions (e.g. trophic relationships) is responsible for the spatial distribution of nematodes. In other words, the physical factors are more important in structuring nematodes communities over large scale of distribution while biological interactions are largely important in finer-scale distributions. It has been accepted that biological interactions are assumed to be of minor importance because physical factors overshadow the biological interactions in sandy beach sediments; however, the most recent results from in-situ and ex-situ experimental investigations on behavior and biological factors on a microscale have shown promise for understanding the mechanisms underlying larger-scale patterns and processes. Besides nematodes are very promising organisms used to understand the effects of pollution and climate changes although these subjects are less studied in sandy beaches than distribution patterns.

Signatures of adaptation to plant parasitism in nematode genomes.

PubMed

Bird, David McK; Jones, John T; Opperman, Charles H; Kikuchi, Taisei; Danchin, Etienne G J

2015-02-01

Plant-parasitic nematodes cause considerable damage to global agriculture. The ability to parasitize plants is a derived character that appears to have independently emerged several times in the phylum Nematoda. Morphological convergence to feeding style has been observed, but whether this is emergent from molecular convergence is less obvious. To address this, we assess whether genomic signatures can be associated with plant parasitism by nematodes. In this review, we report genomic features and characteristics that appear to be common in plant-parasitic nematodes while absent or rare in animal parasites, predators or free-living species. Candidate horizontal acquisitions of parasitism genes have systematically been found in all plant-parasitic species investigated at the sequence level. Presence of peptides that mimic plant hormones also appears to be a trait of plant-parasitic species. Annotations of the few genomes of plant-parasitic nematodes available to date have revealed a set of apparently species-specific genes on every occasion. Effector genes, important for parasitism are frequently found among those species-specific genes, indicating poor overlap. Overall, nematodes appear to have developed convergent genomic solutions to adapt to plant parasitism.

Integrated management of root-knot nematode, Meloidogyne incognita infestation in tomato and grapevine.

PubMed

Kumari, N Swarna; Sivakumar, C V

2005-01-01

An integrated approach with the obligate bacterial parasite, Pasteuria penetrans and nematicides was assessed for the management of the root-knot nematode, Meloidogyne incognita infestation in tomato and grapevine. Seedlings of tomato cv. Co3 were transplanted into pots filled with sterilized soil and inoculated with nematodes (5000 juveniles/pot). The root powder of P. penetrans at 10 mg/pot was applied alone and in combination with carbofuran at 6 mg/pot. Application of P. penetrans along with carbofuran recorded lowest nematode infestation (107 nematodes/200 g soil) compared to control (325 nematodes/200 g soil). The rate of parasitization was 83.1% in the carbofuran and P. penetrans combination treatment as against 61.0% in the P. penetrans treatment only. The plant growth was also higher in the combination treatment compared to all other treatments. A field trial was carried out to assess the efficacy of P. penetrans and nematicides viz., carbofuran and phorate in the management of root-knot nematode, M. incognita infestation of grapevine cv. Muscat Hamburg. A nematode and P. penetrans infested grapevine field was selected and treatments either with carbofuran or phorate at 1 g a.i/vine was given. The observations were recorded at monthly interval. The results showed that the soil nematode population was reduced in nematicide treated plots. Suppression of nematodes was higher under phorate (117 nematodes/200 g soil) than under carbofuran (126.7 nematodes/200 g soil) treatment. The number of juveniles parasitized was also influenced by nematicides and spore load carried/juvenile with phorate being superior and the increase being 17.0 and 29.0% respectively over the control. The results of these experiment confirmed the compatibility of P. penetrans with nematicides and its biological control potential against the root-knot nematode.

Suppression on plant-parasitic nematodes using a soil fumigation strategy based on ammonium bicarbonate and its effects on the nematode community

PubMed Central

Su, Lanxi; Ruan, Yunze; Yang, Xiujuan; Wang, Kang; Li, Rong; Shen, Qirong

2015-01-01

Banana production is severely hindered by plant-parasitic nematodes in acidic, sandy soil. This study investigated the possibility of applying a novel fumigation agent based on ammonium bicarbonate as a strategy for controlling plant-parasitic nematodes under sealed conditions. Moreover, its effects on the nematode community in pot and field experiments were also measured using morphology and feeding-habit based classification and the PCR-DGGE method. Results showed that a mixture (LAB) of lime (L) and ammonium bicarbonate (AB) in suitable additive amounts (0.857 g kg−1 of L and 0.428 g kg−1 of AB) showed stronger nematicidal ability than did the use of AB alone or the use of ammonium hydroxide (AH) and calcium cyanamide (CC) with an equal nitrogen amount. The nematode community was altered by the different fumigants, and LAB showed an excellent plant-parasitic nematicidal ability, especially for Meloidogyne and Rotylenchulus, as revealed by morphology and feeding-habit based classification, and for Meloidogyne, as revealed by the PCR-DGGE method. Fungivores and omnivore-predators were more sensitive to the direct effects of the chemicals than bacterivores. This study explored a novel fumigation agent for controlling plant-parasitic nematodes based on LAB and provides a potential strategy to ensure the worldwide development of the banana industry. PMID:26621630

Development and reproductive potential of Tyrophagus putrescentiae (Acari: Acaridae) on plant-parasitic nematodes and artificial diets.

PubMed

Abou El-Atta, Doaa Abd El-Maksoud; Osman, Mohamed Ali

2016-04-01

This study investigated development, reproduction and life table parameters of the astigmatid mold mite Tyrophagus putrescentiae (Schrank) (Acari: Acaridae) feeding on egg-masses or adult females of the nematode Meloidogyne incognita, egg-masses of the nematode Rotylenchulus reniformis, ras cheese or yeast at 25 ± 1 °C, 70 ± 10 % RH in the dark. Immature developmental times were shorter when the mite was fed females of M. incognita followed by yeast. Different prey/diet types had no significant effect on longevity and lifespan of both males and females. Daily oviposition rate (eggs/female/day) was highest for mites fed yeast (20.8 ± 1.8 eggs) and lowest for mites fed females of M. incognita (6.6 ± 0.5). Intrinsic rate of natural increase (r m) was highest for mites fed yeast compared to other prey/diet; no significant differences in r m were observed among mites fed on non-yeast diets. This result may suggest a role of T. putrescentiae as biocontrol agent of plant-parasitic nematodes and the yeast may be used for mite mass-production purposes.

Sex-specific mating pheromones in the nematode Panagrellus redivivus

USDA-ARS?s Scientific Manuscript database

Despite advances in medicine and crop genetics, nematodes remain significant human pathogens and agricultural pests. This warrants investigation of alternative strategies for pest control, such as interference with pheromone-mediated reproduction. Because only two nematode species have had their phe...

RNAseq Analysis of the Drosophila Response to the Entomopathogenic Nematode Steinernema.

PubMed

Yadav, Shruti; Daugherty, Sean; Shetty, Amol Carl; Eleftherianos, Ioannis

2017-06-07

Drosophila melanogaster is an outstanding model to study the molecular and functional basis of host-pathogen interactions. Currently, our knowledge of microbial infections in D. melanogaster is well understood; however, the response of flies to nematode infections is still in its infancy. Here, we have used the potent parasitic nematode Steinernema carpocapsae , which lives in mutualism with its endosymbiotic bacteria Xenorhabdus nematophila , to examine the transcriptomic basis of the interaction between D. melanogaster and entomopathogenic nematodes. We have employed next-generation RNA sequencing (RNAseq) to investigate the transcriptomic profile of D. melanogaster larvae in response to infection by S. carpocapsae symbiotic (carrying X. nematophila ) or axenic (lacking X. nematophila ) nematodes. Bioinformatic analyses have identified the strong induction of genes that are associated with the peritrophic membrane and the stress response, as well as several genes that participate in developmental processes. We have also found that genes with different biological functions are enriched in D. melanogaster larvae responding to either symbiotic or axenic nematodes. We further show that while symbiotic nematode infection enriched certain known immune-related genes, axenic nematode infection enriched several genes associated with chitin binding, lipid metabolic functions, and neuroactive ligand receptors. In addition, we have identified genes with a potential role in nematode recognition and genes with potential antinematode activity. Findings from this study will undoubtedly set the stage for the identification of key regulators of antinematode immune mechanisms in D. melanogaster , as well as in other insects of socioeconomic importance. Copyright © 2017 Yadav et al.

The Mesostigmatid Mite Protogamasellus mica, an Effective Predator of Free-Living and Plant-Parasitic Nematodes.

PubMed

Stirling, Graham R; Stirling, A Marcelle; Walter, David E

2017-09-01

Protogamasellus mica was extracted from a sugarcane field in Australia and cultured on bacterial-feeding nematodes. Studies with various nematodes in laboratory arenas showed that one mite and its progeny reduced nematode numbers by between 26 and 50 nematodes/day. A bacterivore ( Mesorhabditis sp.), a fungivore ( Aphelenchus avenae ), and two plant parasites (root-knot nematode, Meloidogyne javanica and root-lesion nematode, Pratylenchus zeae ) were all reduced at much the same rate despite the fact that the nematodes are quite different in size and motility and belong to different trophic groups. When sugarcane was grown in the greenhouse for 8 wk, stunt nematode ( Tylenchorhynchus annulatus ), a plant parasite that feeds ectoparasitically on roots, was almost eliminated from pots inoculated with the mite, and numbers of microbivores and root-lesion nematode were markedly reduced. Huge reductions in nematode populations were also observed when mites were added to microcosms containing small quantities of defaunated soil. These results show that P. mica multiplies rapidly when nematodes are available as a food source and has the capacity to play a role in regulating populations of both plant-parasitic and free-living nematodes. Future research should focus on understanding the crop and soil management practices required to enable this mite and other predatory species to thrive.

Impact of eprinomectin on grazing behaviour and performance in dairy cattle with sub-clinical gastrointestinal nematode infections under continuous stocking management.

PubMed

Forbes, A B; Huckle, C A; Gibb, M J

2004-11-10

Forty spring-calving cows and heifers (20 of each) were allowed to acquire infection with gastrointestinal (GI) nematodes naturally during grazing. The control group (10 cows and 10 heifers) were compared with 20 similar animals treated with eprinomectin in order to evaluate the effect of GI nematodes on grazing behaviour, milk production, body condition score and live weight. The animals were paired according to parity and milk yield during the week prior to treatment, then within replicate pair randomly allocated to a different treatment group. The grazing area was sub-divided into 20 replicated paddocks of equivalent size and topography. Grazing pairs of either control or treated animals were randomly assigned to each paddock over the duration of the study (one pair per paddock). Grazing behaviour was recorded for both groups over a 10-day period commencing 4 days after treatment with eprinomectin. Milk yield was recorded daily and milk quality was recorded weekly. Live weight and body condition score were recorded on the day of allocation, the day of initial treatment and thereafter at weekly intervals until the end of the 4-week trial. Faecal samples were collected from each animal prior to, and after, allocation and submitted for counts of nematode eggs. Additional faecal samples were taken at the end of the study for culture and nematode identification. Individual faecal samples were also analysed for residual digestibility. Pasture samples for nematode larval counts were taken at the same time as faecal sampling. The parasitological results showed low levels of faecal nematode egg output throughout the study, with the heifers having higher counts than the cows. Faecal culture yielded species of Ostertagia, Cooperia, and Trichostrongylus. Pasture larval levels were very low throughout with no value exceeding 68 larvae/kg dry matter (DM) of herbage. There were significant (P < 0.05) effects of treatment on grazing time, eating time, total bites, total grazing

Identification of candidate infection genes from the model entomopathogenic nematode Heterorhabditis bacteriophora.

PubMed

Vadnal, Jonathan; Ratnappan, Ramesh; Keaney, Melissa; Kenney, Eric; Eleftherianos, Ioannis; O'Halloran, Damien; Hawdon, John M

2017-01-03

Despite important progress in the field of innate immunity, our understanding of host immune responses to parasitic nematode infections lags behind that of responses to microbes. A limiting factor has been the obligate requirement for a vertebrate host which has hindered investigation of the parasitic nematode infective process. The nematode parasite Heterorhabditis bacteriophora offers great potential as a model to genetically dissect the process of infection. With its mutualistic Photorhabdus luminescens bacteria, H. bacteriophora invades multiple species of insects, which it kills and exploits as a food source for the development of several nematode generations. The ability to culture the life cycle of H. bacteriophora on plates growing the bacterial symbiont makes it a very exciting model of parasitic infection that can be used to unlock the molecular events occurring during infection of a host that are inaccessible using vertebrate hosts. To profile the transcriptional response of an infective nematode during the early stage of infection, we performed next generation RNA sequencing on H. bacteriophora IJs incubated in Manduca sexta hemolymph plasma for 9 h. A subset of up-regulated and down-regulated genes were validated using qRT-PCR. Comparative analysis of the transcriptome with untreated controls found a number of differentially expressed genes (DEGs) which cover a number of different functional categories. A subset of DEGs is conserved across Clade V parasitic nematodes revealing an array of candidate parasitic genes. Our analysis reveals transcriptional changes in the regulation of a large number of genes, most of which have not been shown previously to play a role in the process of infection. A significant proportion of these genes are unique to parasitic nematodes, suggesting the identification of a group of parasitism factors within nematodes. Future studies using these candidates may provide functional insight into the process of nematode parasitism

Efficacy of doramectin injectable against Oestrus ovis and gastrointestinal nematodes in sheep in the southwestern region of France.

PubMed

Dorchies, P; Jacquiet, P; Bergeaud, J P; Duranton, C; Prévot, F; Alzieu, J P; Gossellin, J

2001-03-20

A study was conducted to evaluate the therapeutic efficacy of doramectin administered intramuscularly at a dose rate of 200 microg/kg to sheep harbouring naturally acquired infections of gastrointestinal nematodes and Oestrus ovis in the southwestern region of France. On day 0, 24 sheep were selected on the basis of positive faecal egg counts (>100 EPG) and positive assessment of O. ovis infection (including positive O. ovis antibody level and positive clinical score). The sheep were randomly allocated to a non-medicated control group (T1) or a doramectin-treated group (T2) of 12 animals each. On day 0, sheep in group T2 received a single intramuscular injection of doramectin (200 microg/kg), whereas those in group T1 received an intramuscular injection of saline solution (sodium chloride, 0.02ml/kg). Individual faecal egg counts were performed on days 0, 1, 2, 3, 4, 5, 6, 7, and 14. Between days 14 and 16, all sheep were slaughtered, and worm and O. ovis burdens were determined. In doramectin-treated sheep, faecal egg counts had decreased to zero by day 4 for all recovered types of nematode eggs: strongyles, Nematodirus sp., Trichuris sp., and Rhabditidae sp. For strongyles, Nematodirus sp., and Rhabditidae, the percentage reductions in faecal egg counts (geometric means) of doramectin-treated sheep, compared to the non-medicated control sheep were 100% from days 4-7. For Trichuris sp., they were 100, 99.7, 99.9, and 100% on days 4, 5, 6, and 7, respectively. On day 14, percentage reductions were 100% for Nematodirus sp. and Rhabditidae, and 99.8 and 99.1% for strongyles and Trichuris sp., respectively. At necropsy, only adult nematodes and mainly first-stage O. ovis larvae were recovered. Doramectin was highly efficacious against the adult stages of Teladorsagia circumcincta (100%), Nematodirus battus (100%), Nematodirus filicollis (99.9%), Oesophagostomum venulosum (99.8%), and Trichuris sp. (99.3%). It was also 100% efficacious against first-stage larvae of O

First report of the root-lesion nematode, Pratylenchus scribneri, infecting potato in North Dakota

USDA-ARS?s Scientific Manuscript database

Root-lesion nematodes (Pratylenchus spp.) are the most common nematode pests of potato. Five soil samples were collected from a harvested potato field near Cogswell (Sargent County), ND in October 2014 to investigate the occurrence of root-lesion nematodes. Plant-parasitic nematodes were extracted, ...

Post-Miocene expansion, colonization, and host switching drove speciation among extant nematodes of the archaic genus Trichinella

PubMed Central

Zarlenga, D. S.; Rosenthal, B. M.; La Rosa, G.; Pozio, E.; Hoberg, E. P.

2006-01-01

Parasitic nematodes of the genus Trichinella cause significant food-borne illness and occupy a unique evolutionary position at the base of the phylum Nematoda, unlike the free-living nematode Caenorhabditis elegans. Although the forthcoming genome sequence of Trichinella spiralis can provide invaluable comparative information about nematode biology, a basic framework for understanding the history of the genus Trichinella is needed to maximize its utility. We therefore developed the first robust and comprehensive analysis of the phylogeny and biogeographic history of Trichinella using the variation in three genes (nuclear small-subunit rDNA, and second internal transcribed spacer, mitochondrial large-subunit rDNA, and cytochrome oxidase I DNA) from all 11 recognized taxa. We conclude that (i) although Trichinellidae may have diverged from their closest extant relatives during the Paleozoic, all contemporary species of Trichinella diversified within the last 20 million years through geographic colonization and pervasive host switching among foraging guilds of obligate carnivores; (ii) mammalian carnivores disseminated encapsulated forms from Eurasia to Africa during the late Miocene and Pliocene, and to the Nearctic across the Bering Land Bridge during the Pliocene and Pleistocene, when crown species ultimately diversified; (iii) the greatest risk to human health is posed by those species retaining an ancestral capacity to parasitize a wide range of hosts; and (iv) early hominids may have first acquired Trichinella on the African savannah several million years before swine domestication as their diets shifted from herbivory to facultative carnivory. PMID:16651518

Prevalence of Pasteuria SP. on Renfirom Nematode in a Georgia Cotton Field

USDA-ARS?s Scientific Manuscript database

Pasteuria species are bacterial parasites of nematodes and have been associated with suppression of root-knot, sting, and cyst nematode populations. Little is known about the Pasteuria sp. infecting the reniform nematode. While sampling a cotton field study near Cochran, GA, we found Pasteuria spo...

Latitudinal variation in nematode diversity and ecological roles along the Chinese coast.

PubMed

Wu, Jihua; Chen, Huili; Zhang, Youzheng

2016-11-01

To test changes in the phylogenetic relatedness, niche breadth, and life-history strategies of nematodes along a latitudinal gradient. Sixteen wetland locations along the Pacific coast of China, from 20°N to 40°N. Linear regression was used to relate nematode phylogenetic relatedness (average taxonomic distinctness (AvTD) and average phylogenetic diversity [AvPD]), life-history group (based on " c - p " colonizer-persister group classification), and dietary specificity (based on guild classification of feeding selectivity) to latitude. Wetland nematode taxonomic diversity (richness and Shannon diversity indices) decreased with increasing latitude along the Chinese coast. Phylogenetic diversity indices (AvTD and AvPD) significantly increased with increasing latitude. This indicates that at lower latitudes, species within the nematode community were more closely related. With increasing latitude, the nematode relative richness and abundance decreased for selective deposit feeders but increased for nonselective deposit feeders. The proportion of general opportunists decreased with increasing latitude, but persisters showed the opposite trend. The annual temperature range and the pH of sediments were more important than vegetation type in structuring nematode communities. Nematode niche breadth was narrower at lower latitudes with respect to dietary specificity. Higher latitudes with a more variable climate favor r over K life-history strategists. Nematode communities at lower latitudes contained more closely related species.

Life history trait analysis of the entomopathogenic nematode Steinernema feltiae provides the basis for prediction of dauer juvenile yields in monoxenic liquid culture.

PubMed

Addis, Temesgen; Teshome, Asmamaw; Strauch, Olaf; Ehlers, Ralf-Udo

2016-05-01

Entomopathogenic nematodes (Steinernema spp.) are used in integrated pest management to control insect pests in cryptic environments. The nematodes are mass produced in monoxenic liquid culture with their symbiotic bacteria Xenorhabdus spp. For a better understanding of nematode population dynamics, the life history traits (LHTs) of the entomopathogenic nematode Steinernema feltiae were assessed at 25 °C by observing single pairs of male and female nematodes using a hanging drop technique. To investigate the influence of different food supplies on nematode reproduction, the LHTs were assessed with a daily supply of 5 ×, 10 × and 20 × 10(9) cells ml(-1) of the nematode's bacterial symbiont Xenorhabdus bovienii in semi-solid nematode growth gelrite (NGG) medium. Increasing bacterial density had a significant positive influence on the average number of offspring produced, which ranged from 359 to 813 per female. The intrinsic rate of natural increase r m, which ranges from 1.10 to 1.19 day(-1), was neither influenced by the bacterial density, nor was the mean generation time T (5.12-5.25 days) and population doubling time (PDT) (0.64-0.59 days). The average lifespan of reproductive females, which ranged from 6.7 to 7.3 days, was positively correlated with bacterial density. A positive correlation between female body volume and bacterial density was recorded (R = 0.67) as well as a significant positive correlation between female body size and offspring production (R = 0.89) in hanging drops. Whether these data can be used to predict nematode yields in liquid culture was tested. The total female body volume calculated as the average female body volume × total number of parental females per millilitre 3 days after nematode inoculation was positively correlated (R = 0.72) with nematode yields. The total female body volume on process day 3 is thus a good indicator for the estimation of nematode yield at the end of the process (12-15 days post dauer

Genome-wide association study uncovers a novel QTL allele of AtS40-3 that affects the sex ratio of cyst nematodes in Arabidopsis.

PubMed

Anwer, Muhammad Arslan; Anjam, Muhammad Shahzad; Shah, Syed Jehangir; Hasan, M Shamim; Naz, Ali A; Grundler, Florian M W; Siddique, Shahid

2018-03-24

Plant-parasitic cyst nematodes are obligate sedentary parasites that infect the roots of a broad range of host plants. Cyst nematodes are sexually dimorphic, but differentiation into male or female is strongly influenced by interactions with the host environment. Female populations typically predominate under favorable conditions, whereas male populations predominate under adverse conditions. Here, we performed a genome-wide association study (GWAS) in an Arabidopsis diversity panel to identify host loci underlying variation in susceptibility to cyst nematode infection. Three different susceptibility parameters were examined, with the aim of providing insights into the infection process, the number of females and males present in the infected plant, and the female-to-male sex ratio. GWAS results suggested that variation in sex ratio is associated with a novel quantitative trait locus allele on chromosome 4. Subsequent candidate genes and functional analyses revealed that a senescence-associated transcription factor, AtS40-3, and PPR may act in combination to influence nematode sex ratio. A detailed molecular characterization revealed that variation in nematode sex ratio was due to the disturbed common promoter of AtS40-3 and PPR genes. Additionally, single nucleotide polymorphisms in the coding sequence of AtS40-3 might contribute to the natural variation in nematode sex ratio.

Nematodes in Dryland Field Crops in the Semiarid Pacific Northwest United States

PubMed Central

Smiley, Richard W.; Merrifield, Kathy; Patterson, Lisa-Marie; Whittaker, Ruth G.; Gourlie, Jennifer A.; Easley, Sandra A.

2004-01-01

Soils and roots of field crops in low-rainfall regions of the Pacific Northwest were surveyed for populations of plantparasitic and non-plant-parasitic nematodes. Lesion nematodes (Pratylenchus species) were recovered from 123 of 130 non-irrigated and 18 of 18 irrigated fields. Pratylenchus neglectus was more prevalent than P. thornei, but mixed populations were common. Population densities in soil were affected by crop frequency and rotation but not by tillage or soil type (P < 0.05). Many fields (25%) cropped more frequently than 2 of 4 years had potentially damaging populations of lesion nematodes. Pratylenchus neglectus density in winter wheat roots was inversely correlated with grain yield (r2 = 0.64, P = 0.002), providing the first field-derived evidence that Pratylenchus is economically important in Pacific Northwest dryland field crops. Stunt nematodes (Tylenchorhynchus clarus and Geocenamus brevidens) were detected in 35% of fields and were occasionally present in high numbers. Few fields were infested with pin (Paratylenchus species) and root-knot (Meloidogyne naasi and M. chitwoodi) nematodes. Nematodes detected previously but not during this survey included cereal cyst (Heterodera avenae), dagger (Xiphinema species), and root-gall (Subanguina radicicola) nematodes. PMID:19262788

Nematode infection in fish from Cartagena Bay, North of Colombia.

PubMed

Verbel, Jesús Olivero; Caballero-Gallardo, Karina; Arroyo-Salgado, Bárbara

2011-04-19

Parasitic nematode infection indices were recorded in different fish species collected at Cartagena Bay, North of Colombia. Among 19 studied species, the Mugil genus presented the highest prevalence (83.9-100%), although Sciades herzbergii, Caranx hippos and Centropomus undecimalis were also found infected with nematodes. Parasites were found in the liver, intestinal mesenteries and encysted near the intervertebral joints, with an average parasite abundance of 4.0 ± 0.3 nematodes per fish. Morphological analysis allowed the identification of these nematodes as Contracaecum sp. A small, but positive correlation was found between parasite abundance and length (R=0.294, P<0.001) and weight (R=0.244, P<0.001). In contrast, the correlation between parasite abundance and condition factor was negative (R=-0.191, P<0.001). These results are the first describing the presence of nematodes in several fish species of this ecosystem, and it highlights the need for monitoring parasitism in Mugil species in order to avoid parasite ingestion during fish consumption. Copyright © 2010 Elsevier B.V. All rights reserved.

The cyst nematodes Heterodera and Globodera species in Egypt

USDA-ARS?s Scientific Manuscript database

Information concerning the occurrence and distribution of the cyst nematodes (Heterodera spp. and Globodera spp.) in Egypt is important to assess their potential to cause economic damage to many crop plants. A nematode survey was conducted in Alexandria, El Behera and Sohag governorates during 2012-...

Homologues of the human multidrug resistance genes MRP and MDR contribute to heavy metal resistance in the soil nematode Caenorhabditis elegans.

PubMed Central

Broeks, A; Gerrard, B; Allikmets, R; Dean, M; Plasterk, R H

1996-01-01

Acquired resistance of mammalian cells to multiple chemotherapeutic drugs can result from enhanced expression of the multidrug resistance-associated protein (MRP), which belongs to the ABC transporter superfamily. ABC transporters play a role in the protection of organisms against exogenous toxins by cellular detoxification processes. We have identified four MRP homologues in the soil nematode Caenorhabditis elegans, and we have studied one member, mrp-1, in detail. Using an mrp::lacZ gene fusion, mrp-l expression was found in cells of the pharynx, the pharynx-intestinal valve and the anterior intestinal cells, the rectum-intestinal valve and the epithelial cells of the vulva. Targeted inactivation of mrp-l resulted in increased sensitivity to the heavy metal ions cadmium and arsenite, to which wild-type worms are highly tolerant. The most pronounced effect of the mrp-1 mutation is on the ability of animals to recover from temporary exposure to high concentrations of heavy metals. Nematodes were found to be hypersensitive to heavy metals when both the MRP homologue, mrp-1, and a member of the P-glycoprotein (Pgp) gene family, pgp-1, were deleted. We conclude that nematodes have multiple proteins, homologues of mammalian proteins involved in the cellular resistance to chemotherapeutic drugs, that protect them against heavy metals. Images PMID:8947035

Glutathione peroxidases of the potato cyst nematode Globodera Rostochiensis.

PubMed

Jones, J T; Reavy, B; Smant, G; Prior, A E

2004-01-07

We report the cloning and characterisation of full-length DNAs complementary to RNA (cDNAs) encoding two glutathione peroxidases (GpXs) from a plant parasitic nematode, the potato cyst nematode (PCN) Globodera rostochiensis. One protein has a functional signal peptide that targets the protein for secretion from animal cells while the other is predicted to be intracellular. Both genes are expressed in all parasite stages tested. The mRNA encoding the intracellular GpX is present throughout the nematode second stage juvenile and is particularly abundant in metabolically active tissues including the genital primordia. The mRNA encoding the secreted GpX is restricted to the hypodermis, the outermost cellular layer of the nematode, a location from which it is likely to be secreted to the parasite surface. Biochemical studies confirmed the secreted protein as a functional GpX and showed that, like secreted GpXs of other parasitic nematodes, it does not metabolise hydrogen peroxide but has a preference for larger hydroperoxide substrates. The intracellular protein is likely to have a role in metabolism of active oxygen species derived from internal body metabolism while the secreted protein may protect the parasite from host defences. Other functional roles for this protein are discussed.

Efficacy of a Simple Formulation Composed of Nematode-Trapping Fungi and Bidens pilosa var. radiata Scherff Aqueous Extracts (BPE) for Controlling the Southern Root-Knot Nematode

PubMed Central

Ajitomi, Atsushi; Taba, Satoshi; Ajitomi, Yoshino; Kinjo, Misa; Sekine, Ken-taro

2018-01-01

We tested a formulation composed of a mixture of Bidens pilosa var. radiata extract (BPE) and nematode-trapping fungi for its effects on Meloidogyne incognita. In earlier evaluations of the effects of plant extracts on the hyphal growth of 5 species of nematode-trapping fungi with different capture organs (traps), the growth of all species was slightly inhibited. However, an investigation on the number of capture organs and nematode-trapping rates revealed that Arthrobotrys dactyloides formed significantly more rings and nematode traps than those of the control. An evaluation of simple mixed formulations prepared using sodium alginate showed that nematodes were captured with all formulations tested. The simple mixed formulation showed a particularly high capture rate. Furthermore, in a pot test, although the effects of a single formulation made from the fungus or plant extract were acceptable, the efficacy of the simple mixed formulation against M. incognita root-knot formation was particularly high. PMID:29311429

Phylogenetic analysis of Deladenus nematodes parasitizing northeastern North American Sirex species.

PubMed

Morris, E Erin; Kepler, Ryan M; Long, Stefan J; Williams, David W; Hajek, Ann E

2013-06-01

The parasitic nematode Deladenus siricidicola is a biological control agent of the invasive woodwasp, Sirex noctilio. Since the discovery of S. noctilio in pine forests of northeastern North America in 2005, a biological control program involving the Kamona strain of D. siricidicola has been under consideration. However, North American pine forests have indigenous Sirex spp. and likely harbor a unique assemblage of associated nematodes. We assessed phylogenetic relationships among native Deladenus spp. in the northeastern United States and the Kamona strain of D. siricidicola. We sequenced three genes (mtCO1, LSU, and ITS) from nematodes extracted from parasitized Sirex spp. collected inside and outside of the range of S. noctilio. Our analyses suggest cospeciation between four North American Sirex spp. and their associated nematode parasites. Within two S. noctilio individuals we found nematodes that we hypothesize are normally associated with Sirex nigricornis. One individual of the native S. nigricornis contained Deladenus normally associated with S. noctilio. We discuss nematode-host fidelity in this system and the potential for non-target impacts of a biological control program using D. siricidicola against S. noctilio. Copyright © 2013 Elsevier Inc. All rights reserved.

Resistant nematodes in cattle: Pharmaco-therapeutic assessment of the ivermectin- ricobendazole combination.

PubMed

Canton, Candela; Ceballos, Laura; Fiel, César; Moreno, Laura; Domingo Yagüez, Pablo; Bernat, Gisele; Lanusse, Carlos; Alvarez, Luis

2017-01-30

Nematodicidal combinations have been proposed as a valid strategy to achieve effective nematode control in the presence of drug resistance. The goals of this study were: (1) to compare the clinical efficacy (therapeutic response) of ivermectin (IVM) and ricobendazole (RBZ) given subcutaneously either by separate or combined administration to calves naturally infected with gastrointestinal nematodes resistant to IVM, and (2) to evaluate the potential pharmacokinetic (PK) and/or pharmacodynamic (PD) interactions occurring after the co-administration of both anthelmintics. Sixty male calves naturally infected with gastrointestinal nematodes resistant to IVM were randomly allocated into four groups (n=15). Untreated control: animals not receiving anthelmintic treatment; IVM alone: animals treated with IVM by subcutaneous (SC) injection (0.2mg/kg); RBZ alone: animals received RBZ by the SC route (3.75mg/kg); IVM+RBZ: animals treated with IVM and RBZ (0.2 and 3.75mg/kg, respectively), by SC injection in two separates sites. Eight animals of each treated group were randomly selected to perform the PK study. Plasma samples were taken from those animals up to 28days post-treatment. IVM and RBZ plasma concentrations were quantified by HPLC. The therapeutic response was determined by faecal egg count reduction test (FECRT). The proportions of third-stage larvae (L3) recovered from coprocultures were used to calculate the efficacy against the main parasite genera. The daily total egg deposition for each experimental group was estimated. Similar pharmacokinetic trends were obtained for both IVM and RBZ allying the single-drug and the combined treatments, which indicates the absence of PK interactions between both anthelmintics. The observed overall clinical drug efficacies were 48% (IVM alone), 94% (RBZ alone) and 98% (IVM+RBZ). Haemonchus spp. and Cooperia spp. were recovered in the coproculture after IVM treatment, suggesting that resistance to IVM includes both genera. In

The Effect of Endophytic Fungi on Nematode Populations in Summer-dormant and Summer-active Tall Fescue.

PubMed

Rogers, James K; Walker, Nathan R; Young, Carolyn A

2016-06-01

Summer-active (continental) and summer-dormant (Mediterranean) tall fescue morphotypes are each adapted to different environmental conditions. Endophyte presence provides plant parasitic nematode resistance, but not with all endophyte strains and cultivar combinations. This study sought to compare effects of four nematode genera on continental and Mediterranean cultivars infected with common toxic or novel endophyte strains. A 6-mon greenhouse study was conducted with continental cultivars, Kentucky 31 (common toxic) and Texoma MaxQ II (novel endophyte) and the Mediterranean cultivar Flecha MaxQ (novel endophyte). Endophyte-free plants of each cultivar were controls. Each cultivar × endophyte combination was randomly assigned to a control, low or high inoculation rate of a mixed nematode culture containing stunt nematodes (Tylenchorhynchus spp.), ring nematodes (Criconemella spp.), spiral nematodes (Helicotylenchus spp.), and lesion nematodes (Pratylenchus spp.). Endophyte infection had no effect on nematode population densities. The cultivar × endophyte interaction was significant. Population densities of stunt nematode, spiral nematode, and ring nematodes were higher for Flecha MaxQ than other cultivar × endophyte combinations. Novel endophyte infection enhances suitability of Flecha MaxQ as a nematode host.

Comparative Analysis of Serum Mineral Levels and Parasite Load in Goats Naturally Infected with Gastrointestinal Nematodes.

PubMed

Ünübol Aypak, Serap; Aypak, Süleyman; Voyvoda, Hüseyin; Güven, Gülşen; Dereli Fidan, Evrim; Tosun, Gamze; Gültekin, Mehmet; Şimşek, Emrah; Gülçe Güler, Asude

2016-09-01

This study aimed to investigate the relationship between serum mineral levels and parasite load in Saanen (n=37) and Damascus (n=13) goats, which were all approximately 2 months pregnant and naturally infected with gastrointestinal nematodes. To determine parasite concentration individually, fecal samples were taken from each goat, and the eggs per gram (EPG) of feces was detected via a modified McMaster technique. To investigate the possible effects of parasite concentration on serum mineral levels, blood was drawn from the goats and serum calcium, phosphorus, magnesium, iron, copper, zinc, manganese, nickel, and cadmium levels were measured via the ICP-OES technique. In a correlation analysis of the individual EPG values and mineral levels performed on the basis of the species, it was seen that increased egg numbers did not cause a statistically significant increase or decrease in Saanens except for cadmium (significant moderate positive correlation, p<0.05) for both species. A comparison of the mineral element levels with the lower and upper normal limits in the published literature found that manganese and iron were below the normal range, while zinc and calcium levels were close to the lower limits. It is estimated that the effect of parasite load, which continuously increases with the progression of pregnancy and deliveries, on blood mineral levels would be much more significant.

The draft genome of the parasitic nematode Trichinella spiralis

PubMed Central

Mitreva, Makedonka; Jasmer, Douglas P.; Zarlenga, Dante S.; Wang, Zhengyuan; Abubucker, Sahar; Martin, John; Taylor, Christina M.; Yin, Yong; Fulton, Lucinda; Minx, Pat; Yang, Shiaw-Pyng; Warren, Wesley C.; Fulton, Robert S.; Bhonagiri, Veena; Zhang, Xu; Hallsworth-Pepin, Kym; Clifton, Sandra W.; McCarter, James P.; Appleton, Judith; Mardis, Elaine R.; Wilson, Richard K.

2011-01-01

Genome-based studies of metazoan evolution are most informative when phylogenetically diverse species are incorporated in the analysis. As such, evolutionary trends within and outside the phylum Nematoda have been less revealing by focusing only on comparisons involving Caenorhabditis elegans. Herein, we present a draft of the 64 megabase nuclear genome of Trichinella spiralis, containing 15,808 protein coding genes. This parasitic nematode is an extant member of a clade that diverged early in the evolution of the phylum enabling identification of archetypical genes and molecular signatures exclusive to nematodes. Comparative analyses support intrachromosomal rearrangements across the phylum, disproportionate numbers of protein family deaths over births in parasitic vs. a non-parasitic nematode, and a preponderance of gene loss and gain events in nematodes relative to Drosophila melanogaster. This sequence and the panphylum characteristics identified herein will advance evolutionary studies and strategies to combat global parasites of humans, food animals and crops. PMID:21336279

Potential for Nematode Control by Mycofloras Endemic in the Tropics

PubMed Central

Rodríguez-Kábana, R.; Morgan-Jones, G.

1988-01-01

Results of mycological surveys of root-knot and cyst nematodes from tropical regions indicate that most fungal species associated with females or cysts of species of Globodera, Heterodera, and Meloidogyne are those found with nematodes from temperate areas. Some fungal species, however, were found in higher frequency in tropical regions than in temperate countries; e.g., Cylindrocarpon destructans and Ulocladium atrum were the most common species associated with G. pallida and G. rostochiensis cysts in Peru. These fungi are not so frequent in nematodes from temperate areas. Fungi associated with diseased nematodes in the tropics vary greatly in nutritional requirements and include thermophilic species as well as cold-tolerant fungi. Multi-cropping systems possible in most tropical regions may be designed to increase the frequency of occurrence of microbial species antagonistic to phytonematodes. PMID:19290202

Gastrointestinal nematode infections in sheep raised in Botucatu, state of São Paulo, Brazil.

PubMed

Wilmsen, Maurício Orlando; Silva, Bruna Fernanda; Bassetto, César Cristiano; Amarante, Alessandro Francisco Talamini do

2014-01-01

Gastrointestinal nematode infections were evaluated in sheep raised in Botucatu, state of São Paulo, Brazil between April 2008 and March 2011. Every month, two tracer lambs grazing with a flock of sheep were exposed to natural infection with gastrointestinal nematodes for 28 consecutive days. At the end of this period, the lambs were sacrificed for worm counts. Haemonchus contortus presented 100% of prevalence. The seasons exerted no significant influence on the mean intensity of H. contortus, which ranged from 315 worms in November 2010 to 2,5205 worms in January 2011. The prevalence of Trichostrongylus colubriformis was also 100%, with the lowest mean intensity (15 worms) recorded in February 2011 and the highest (9,760 worms) in October 2009. In the case of T. colubriformis, a significant correlation coefficient was found between worm counts vs. rainfall (r = -0.32; P <0.05). Three other nematodes species were found in tracer lambs, albeit in small numbers. Their prevalence and mean intensity (in parenthesis) were as follows: Oesophagostomum columbianum 28% (25.2), Cooperia curticei 7% (4.5) and Trichuris spp. 2% (1). In conclusion, the environmental conditions of the area proved to be highly favorable for the year-round transmission of H. contortus and T. colubriformis.

TGF-β signaling regulates resistance to parasitic nematode infection in Drosophila melanogaster.

PubMed

Eleftherianos, Ioannis; Castillo, Julio Cesar; Patrnogic, Jelena

2016-12-01

Over the past decade important advances have been made in the field of innate immunity; however, our appreciation of the signaling pathways and molecules that participate in host immune responses to parasitic nematode infections lags behind that of responses to microbial challenges. Here we have examined the regulation and immune activity of Transforming Growth Factor-beta (TGF-β) signaling in the model host Drosophila melanogaster upon infection with the nematode parasites Heterorhabditis gerrardi and H. bacteriophora containing their mutualistic bacteria Photorhabdus. We have found that the genes encoding the Activin and Bone Morphogenic Protein (BMP) ligands Dawdle (Daw) and Decapentaplegic (Dpp) are transcriptionally induced in flies responding to infection with the nematode parasites, containing or lacking their associated bacteria. We also show that deficient Daw or Dpp regulates the survival of D. melanogaster adults to the pathogens, whereas inactivation of Daw reduces the persistence of the nematodes in the mutant flies. These findings demonstrate a novel role for the TGF-β signaling pathways in the host anti-nematode immune response. Understanding the molecular mechanisms of host anti-nematode processes will potentially lead to the development of novel means for the efficient control of parasitic nematodes. Copyright © 2016 Elsevier GmbH. All rights reserved.

Helminth.net: expansions to Nematode.net and an introduction to Trematode.net

PubMed Central

Martin, John; Rosa, Bruce A.; Ozersky, Philip; Hallsworth-Pepin, Kymberlie; Zhang, Xu; Bhonagiri-Palsikar, Veena; Tyagi, Rahul; Wang, Qi; Choi, Young-Jun; Gao, Xin; McNulty, Samantha N.; Brindley, Paul J.; Mitreva, Makedonka

2015-01-01

Helminth.net (http://www.helminth.net) is the new moniker for a collection of databases: Nematode.net and Trematode.net. Within this collection we provide services and resources for parasitic roundworms (nematodes) and flatworms (trematodes), collectively known as helminths. For over a decade we have provided resources for studying nematodes via our veteran site Nematode.net (http://nematode.net). In this article, (i) we provide an update on the expansions of Nematode.net that hosts omics data from 84 species and provides advanced search tools to the broad scientific community so that data can be mined in a useful and user-friendly manner and (ii) we introduce Trematode.net, a site dedicated to the dissemination of data from flukes, flatworm parasites of the class Trematoda, phylum Platyhelminthes. Trematode.net is an independent component of Helminth.net and currently hosts data from 16 species, with information ranging from genomic, functional genomic data, enzymatic pathway utilization to microbiome changes associated with helminth infections. The databases’ interface, with a sophisticated query engine as a backbone, is intended to allow users to search for multi-factorial combinations of species’ omics properties. This report describes updates to Nematode.net since its last description in NAR, 2012, and also introduces and presents its new sibling site, Trematode.net. PMID:25392426

Effect of the spray application technique on the deposition of entomopathogenic nematodes in vegetables.

PubMed

Brusselman, Eva; Beck, Bert; Pollet, Sabien; Temmerman, Femke; Spanoghe, Pieter; Moens, Maurice; Nuyttens, David

2012-03-01

The present study compared entomopathogenic nematode delivery at the base of savoy cabbage and cauliflower, at the lower side of savoy cabbage and cauliflower leaves and in leek stems and the ground deposition using a five-nozzle spray boom equipped with an ISO 08 flat fan, an air induction flat fan and Twinjet spray nozzles. Additionally, an air support system and a row application system were evaluated. Approximately 40% of the applied nematodes did not reach the foot of the cabbage plants. The use of an air support system or a row application system improved nematode deposition at the savoy cabbage base. Relative nematode deposition on the lower side of savoy cabbage leaves was 27.20%, while only 2.64% of the applied nematodes reached the lower side of cauliflower leaves. After spraying leek with a standard boom, a low relative nematode deposition (26.64%) was measured in the leek stem. Nozzle type affected the distribution of nematodes in droplet spots. Nozzle type has a minor effect on the number of entomopathogenic nematodes delivered on difficult-to-reach targets. The use of modified spray application techniques directing the spray to the target site are necessary to increase the chances of contact of entomopathogenic nematodes with their target. Copyright © 2011 Society of Chemical Industry.

77 FR 22185 - Golden Nematode; Removal of Regulated Areas

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-13

..., without change, an interim rule that amended the golden nematode regulations by removing the townships of... that the fields in these two townships are free of golden nematode, and we determined that regulation... the townships of Elba and Byron in Genesee County, NY, from the list of generally infested areas. \\1...

Human Intraocular Filariasis Caused by Pelecitus sp. Nematode, Brazil

PubMed Central

Bain, Odile; Diniz, Daniel G.; Nascimento dos Santos, Jeannie; Pinto de Oliveira, Norimar; Frota de Almeida, Izabela Negrão; Frota de Almeida, Rafael Negrão; Frota de Almeida, Luciana Negrão; Dantas-Torres, Filipe; Sobrinho, Edmundo Frota de Almeida

2011-01-01

A male nematode was extracted from iris fibers of a man from the Brazilian Amazon region. This nematode belonged to the genus Pelecitus but was distinct from the 16 known species in this genus. Similarities with Pelecitus spp. from neotropical birds suggested an avian origin for this species. PMID:21529397

Nematicidal Effects of 5-Aminolevulinic Acid on Plant-Parasitic Nematodes

PubMed Central

Cheng, Feixue; Wang, Jian; Song, Zhiqiang; Cheng, Ju’e; Zhang, Deyong

2017-01-01

Plant-parasitic nematodes are important agricultural pests and often cause serious crop losses. Novel, environmental friendly nematicides are urgently needed because of the harmful effects of some existing nematicides on human health. 5-Aminolevulinic acid (ALA) was reported as a potential biodegradable herbicide, insecticide, or plant-growth promoting agent. Lack of information on ALA against plant-parasitic nematodes prompted this investigation to determine the effects of ALA on Meloidogyne incognita, Heterodera glycines, Pratylenchus coffeae, and Bursaphelenchus xylophilus. A series of in vitro assays and one greenhouse trial were conducted to examine the nematicidal effects of ALA. The results demonstrated that ALA exhibited a strong effect of suppression against the four nematodes tested. ALA also inhibited hatching of M. incognita and H. glycines. Results from the greenhouse experiment indicated that treatment of soil with 6.0 mM ALA significantly reduced the root-gall index (RGI) and egg mass number per root system compared with the uninoculated control (P ≤ 0.05). The metabolism assays indicated that ALA treatment significantly altered the nematode metabolism including the total protein production, malondialdehyde (MDA) content, and oxidase activities. This study suggested that ALA is a promising nematicide against plant-parasitic nematodes. PMID:29062152

Resistance of upland-rice lines to root-knot nematode, Meloidogyne incognita.

PubMed

Souza, D C T; Botelho, F B S; Rodrigues, C S; Furtini, I V; Smiderle, E C; de Matos, D L; Bruzi, A T

2015-12-21

Despite the benefits of crop rotation, occurrence of nematodes is a common problem for almost all crops within the Cerrado biome, especially for rice. The use of resistant cultivars is one of the main methods for control of nematodes. Thus, the present study aimed to evaluate the reaction of 36 upland-rice lines, with desirable agronomic characteristics, according to their resistance to root-knot nematodes (Meloidogyne incognita). The experimental design was entirely randomized with four replications. Each plot of land consisted of two rice plants in a 3-L vase. The plants were inoculated with 1000 eggs and eventual juveniles of the respective nematodes. Fifty-five days after the inoculation, the roots and the aerial part of the plant were weighed and the egg mass (EM) as well as the reproduction factor (Rf) were estimated. It was determined that the isolated use of EM was not beneficial in selecting rice lines resistant to the root-knot nematode. This procedure must, therefore, take into account the egg counting and the Rf, in order to improve the reliability of the selection. In our study, 30 evaluated lines were observed to be resistant. Among the recommended cultivars, only BRS Monarca had its performance susceptible to the studied nematode species.

The gastropod shell has been co-opted to kill parasitic nematodes.

PubMed

Rae, R

2017-07-06

Exoskeletons have evolved 18 times independently over 550 MYA and are essential for the success of the Gastropoda. The gastropod shell shows a vast array of different sizes, shapes and structures, and is made of conchiolin and calcium carbonate, which provides protection from predators and extreme environmental conditions. Here, I report that the gastropod shell has another function and has been co-opted as a defense system to encase and kill parasitic nematodes. Upon infection, cells on the inner layer of the shell adhere to the nematode cuticle, swarm over its body and fuse it to the inside of the shell. Shells of wild Cepaea nemoralis, C. hortensis and Cornu aspersum from around the U.K. are heavily infected with several nematode species including Caenorhabditis elegans. By examining conchology collections I show that nematodes are permanently fixed in shells for hundreds of years and that nematode encapsulation is a pleisomorphic trait, prevalent in both the achatinoid and non-achatinoid clades of the Stylommatophora (and slugs and shelled slugs), which diverged 90-130 MYA. Taken together, these results show that the shell also evolved to kill parasitic nematodes and this is the only example of an exoskeleton that has been co-opted as an immune system.

Soil nematode assemblages as bioindicators of radiation impact in the Chernobyl Exclusion Zone.

PubMed

Lecomte-Pradines, C; Bonzom, J-M; Della-Vedova, C; Beaugelin-Seiller, K; Villenave, C; Gaschak, S; Coppin, F; Dubourg, N; Maksimenko, A; Adam-Guillermin, C; Garnier-Laplace, J

2014-08-15

In radioecology, the need to understand the long-term ecological effects of radioactive contamination has been emphasised. This requires that the health of field populations is evaluated and linked to an accurate estimate of received radiological dose. The aim of the present study was to assess the effects of current radioactive contamination on nematode assemblages at sites affected by the fallout from the Chernobyl accident. First, we estimated the total dose rates (TDRs) absorbed by nematodes, from measured current soil activity concentrations, Dose Conversion Coefficients (DCCs, calculated using EDEN software) and soil-to-biota concentration ratios (from the ERICA tool database). The impact of current TDRs on nematode assemblages was then evaluated. Nematodes were collected in spring 2011 from 18 forest sites in the Chernobyl Exclusion Zone (CEZ) with external gamma dose rates, measured using radiophotoluminescent dosimeters, varying from 0.2 to 22 μGy h(-1). These values were one order of magnitude below the TDRs. A majority of bacterial-, plant-, and fungal-feeding nematodes and very few of the disturbance sensitive families were identified. No statistically significant association was observed between TDR values and nematode total abundance or the Shannon diversity index (H'). The Nematode Channel Ratio (which defines the relative abundance of bacterial- versus fungal-feeding nematodes) decreased significantly with increasing TDR, suggesting that radioactive contamination may influence nematode assemblages either directly or indirectly by modifying their food resources. A greater Maturity Index (MI), usually characterising better soil quality, was associated with higher pH and TDR values. These results suggest that in the CEZ, nematode assemblages from the forest sites were slightly impacted by chronic exposure at a predicted TDR of 200 μGy h(-1). This may be imputable to a dominant proportion of pollutant resistant nematodes in all sites. This might

The Role of Cytokinin During Infection of Arabidopsis thaliana by the Cyst Nematode Heterodera schachtii.

PubMed

Shanks, Carly M; Rice, J Hollis; Zubo, Yan; Schaller, G Eric; Hewezi, Tarek; Kieber, Joseph J

2016-01-01

Plant-parasitic cyst nematodes induce the formation of hypermetabolic feeding sites, termed syncytia, as their sole source of nutrients. The formation of the syncytium is orchestrated by the nematode, in part, by modulation of phytohormone responses, including cytokinin. In response to infection by the nematode Heterodera schachtii, cytokinin signaling is transiently induced at the site of infection and in the developing syncytium. Arabidopsis lines with reduced cytokinin sensitivity show reduced susceptibility to nematode infection, indicating that cytokinin signaling is required for optimal nematode development. Furthermore, lines with increased cytokinin sensitivity also exhibit reduced nematode susceptibility. To ascertain why cytokinin hypersensitivity reduces nematode parasitism, we examined the transcriptomes in wild type and a cytokinin-hypersensitive type-A arr Arabidopsis mutant in response to H. schachtii infection. Genes involved in the response to biotic stress and defense response were elevated in the type-A arr mutant in the absence of nematodes and were hyperinduced following H. schachtii infection, which suggests that the Arabidopsis type-A arr mutants impede nematode development because they are primed to respond to pathogen infection. These results suggest that cytokinin signaling is required for optimal H. schachtii parasitism of Arabidopsis but that elevated cytokinin signaling triggers a heightened immune response to nematode infection.

Quantitative detection of the potato cyst nematode, Globodera pallida, and the beet cyst nematode, Heterodera schachtii, using Real-Time PCR with SYBR green I dye.

PubMed

Madani, Mehrdad; Subbotin, Sergei A; Moens, Maurice

2005-04-01

The potato cyst nematode Globodera pallida and the beet cyst nematode Heterodera schachtii are major nematode pests in world agriculture. Precise identification and knowledge about the number of nematodes in field soil are necessary to develop effective integrated pest control. Here we report the results of the Real-Time PCR assay for the rapid detection and quantification of G. pallida and H. schachtii. Using species specific primers and SYBR green I dye, we were able to detect a single second stage juvenile of cyst forming nematodes in samples. The specificity of the reaction was confirmed by the lack of amplification of DNAs from other Heterodera or Globodera species. Validation tests showed a rather high correlation between real numbers of second stage juveniles in a sample and expected numbers detected by Real-Time PCR. Reasons for observed differences in sensitivity and reliability of quantification detection for two species as well as other problems of Real-Time PCR are discussed. The Real-Time PCR assay with SYBR green I dye targeting fragments of the ITS-rDNA provided a sensitive means for the rapid and simultaneous detection and quantification of juveniles of these pests.

Susceptibility to Ticks and Lyme Disease Spirochetes Is Not Affected in Mice Coinfected with Nematodes.

PubMed

Maaz, Denny; Rausch, Sebastian; Richter, Dania; Krücken, Jürgen; Kühl, Anja A; Demeler, Janina; Blümke, Julia; Matuschka, Franz-Rainer; von Samson-Himmelstjerna, Georg; Hartmann, Susanne

2016-05-01

Small rodents serve as reservoir hosts for tick-borne pathogens, such as the spirochetes causing Lyme disease. Whether natural coinfections with other macroparasites alter the success of tick feeding, antitick immunity, and the host's reservoir competence for tick-borne pathogens remains to be determined. In a parasitological survey of wild mice in Berlin, Germany, approximately 40% of Ixodes ricinus-infested animals simultaneously harbored a nematode of the genus Heligmosomoides We therefore aimed to analyze the immunological impact of the nematode/tick coinfection as well as its effect on the tick-borne pathogen Borrelia afzelii Hosts experimentally coinfected with Heligmosomoides polygyrus and larval/nymphal I. ricinus ticks developed substantially stronger systemic type 2 T helper cell (Th2) responses, on the basis of the levels of GATA-3 and interleukin-13 expression, than mice infected with a single pathogen. During repeated larval infestations, however, anti-tick Th2 reactivity and an observed partial immunity to tick feeding were unaffected by concurrent nematode infections. Importantly, the strong systemic Th2 immune response in coinfected mice did not affect susceptibility to tick-borne B. afzelii An observed trend for decreased local and systemic Th1 reactivity against B. afzelii in coinfected mice did not result in a higher spirochete burden, nor did it facilitate bacterial dissemination or induce signs of immunopathology. Hence, this study indicates that strong systemic Th2 responses in nematode/tick-coinfected house mice do not affect the success of tick feeding and the control of the causative agent of Lyme disease. Copyright © 2016 Maaz et al.

Development of a transformation system for Hirsutella spp. and visualization of the mode of nematode infection by GFP-labeled H. minnesotensis.

PubMed

Sun, Jingzu; Park, Sook-Young; Kang, Seogchan; Liu, Xingzhong; Qiu, Junzhi; Xiang, Meichun

2015-07-20

Hirsutella rhossiliensis and H. minnesotensis are endoparasitic fungi of the second-stage juvenile (J2) of the soybean cyst nematode (Heterodera glycines) in nature. They also parasitize both H. glycines J2 and Caenorhabditis elegans on agar plates. Agrobacterium tumefaciens-mediated transformation conditions were established for these Hirsutella spp. The resulting transformants were similar to the corresponding wild-type strains. The infection processes of H. glycines J2 and C. elegans second larval stage (L2) by H. minnesotensis expressing ZsGreen were microscopically analyzed. Conidia of H. minnesotensis adhered to passing nematodes within 8 h post-inoculation (hpi), formed an infection peg between 8 and 12 hpi, and penetrated the nematode cuticle between 12 and 24 hpi for C. elegans L2 and between 12 and 32 hpi for H. glycines J2. Hyphal proliferation inside of the nematode coelom was observed at approximately 32 hpi for C. elegans L2 and at approximately 40 hpi for H. glycines J2. The fungus consumed the whole body and grew out to produce conidia at approximately 156 and 204 hpi for C. elegans L2 and H. glycines J2, respectively. The efficient transformation protocol and a better understanding of infection process provide a solid foundation for studying the molecular and cellular mechanisms underlying fungal parasitism of nematodes.

Co-evolution of SNF spliceosomal proteins with their RNA targets in trans-splicing nematodes.

PubMed

Strange, Rex Meade; Russelburg, L Peyton; Delaney, Kimberly J

2016-08-01

Although the mechanism of pre-mRNA splicing has been well characterized, the evolution of spliceosomal proteins is poorly understood. The U1A/U2B″/SNF family (hereafter referred to as the SNF family) of RNA binding spliceosomal proteins participates in both the U1 and U2 small interacting nuclear ribonucleoproteins (snRNPs). The highly constrained nature of this system has inhibited an analysis of co-evolutionary trends between the proteins and their RNA binding targets. Here we report accelerated sequence evolution in the SNF protein family in Phylum Nematoda, which has allowed an analysis of protein:RNA co-evolution. In a comparison of SNF genes from ecdysozoan species, we found a correlation between trans-splicing species (nematodes) and increased phylogenetic branch lengths of the SNF protein family, with respect to their sister clade Arthropoda. In particular, we found that nematodes (~70-80 % of pre-mRNAs are trans-spliced) have experienced higher rates of SNF sequence evolution than arthropods (predominantly cis-spliced) at both the nucleotide and amino acid levels. Interestingly, this increased evolutionary rate correlates with the reliance on trans-splicing by nematodes, which would alter the role of the SNF family of spliceosomal proteins. We mapped amino acid substitutions to functionally important regions of the SNF protein, specifically to sites that are predicted to disrupt protein:RNA and protein:protein interactions. Finally, we investigated SNF's RNA targets: the U1 and U2 snRNAs. Both are more divergent in nematodes than arthropods, suggesting the RNAs have co-evolved with SNF in order to maintain the necessarily high affinity interaction that has been characterized in other species.

Toxicity of 2,4-diacetylphloroglucinol (DAPG) to plant-parasitic and bacterial-feeding nematodes.

PubMed

Meyer, Susan L F; Halbrendt, John M; Carta, Lynn K; Skantar, Andrea M; Liu, Ting; Abdelnabby, Hazem M E; Vinyard, Bryan T

2009-12-01

The antibiotic 2,4-diacetylphloroglucinol (DAPG) is produced by some isolates of the beneficial bacterium Pseudomonas fluorescens. DAPG is toxic to many organisms, and crop yield increases have been reported after application of DAPG-producing P. fluorescens. This study was conducted to determine whether DAPG is toxic to selected nematodes. The plant-parasitic nematodes Heterodera glycines, Meloidogyne incognita, Pratylenchus scribneri and Xiphinema americanum, and the bacterial-feeding nematodes Caenorhabditis elegans, Pristionchus pacificus, and Rhabditis rainai, were immersed in concentrations ranging from 0 to 100 μg/ml DAPG. Egg hatch and viability of juveniles and adults were determined. DAPG was toxic to X. americanum adults, with an LD₅₀ of 8.3 μg/ml DAPG. DAPG decreased M. incognita egg hatch, but stimulated C. elegans hatch during the first hours of incubation. Viability of M. incognita J2 and of C. elegans J1 and adults was not affected. There were no observed effects on the other nematodes. The study indicated that DAPG is not toxic to all nematodes, and did not affect the tested species of beneficial bacterial-feeding nematodes. Augmentation of DAPG-producing P. fluorescens populations for nematode biocontrol could be targeted to specific nematode species known to be affected by this compound and by other antibiotics produced by the bacteria, or these bacteria could be used for other possible effects, such as induced plant resistance.

Nematode management in pecans

USDA-ARS?s Scientific Manuscript database

In 2002, the pecan root-knot nematode (Meloidogyne partityla = PRKN) was found on pecan in the southeastern U.S. and was associated with stressed trees exhibiting dead branches in the upper canopy and (or) typical mouse ear (ME) associated foliar symptoms. This research evaluates the host susceptib...

Response of Pinus ponderosa Seedlings to Stylet-Bearing Nematodes

PubMed Central

Viglierchio, D. R.

1979-01-01

Of 12 stylet-bearing nematodes used for inoculations, Pratylenchus penetrans, P. brachyurus, P. vulnus, Ditylenchus destructor, Meloidogyne incognita, M. javanica, and M. hapla reproduced on Pinus ponderosa, while Xiphinema index, Aphelenchus avenae, Paratylenehus neoamblycephalus, Tylenchulus semipenetrans, and Macroposthonia xenoplax did not. P. vulnus, P. brachyurus, P. penetrans, A. avenae, D. destructor, T. semipenetrans, and P. neoamblycephalus significantly suppressed both the shoot and root wet weights of ponderosa pine seedlings obtained from stands in five different locations. X. index significantly suppressed root wet weights, M. xenoplax siguificantly suppressed shoot wet weight, and M. incognita, M. javanica, and M. hapla suppressed neither at the inoculation levels used. Injurious nematodes tended to suppress root growth more than shoot growth. Seedlings from two locations produced greater shoot growth wet weight than did seedlings from the other three locations. The more injurious nematodes tended to cause an increase in the water content of shoots. Frequency analyses of seedling population shoot-root ratios indicated that ponderosa pine seedlings could be selected for better shoot-root ratios as well as for resistance to several pathogenic nematodes. PMID:19300659

A SNARE-like protein and biotin are implicated in soybean cyst nematode virulence

USDA-ARS?s Scientific Manuscript database

Some phytoparasitic nematodes have the ability to infect and reproduce on plants that are normally considered resistant to nematode infection. Such nematodes are referred to as virulent and the mechanisms they use to evade or suppress host plant defenses are not well understood. Here, we report the ...

Identification and activity of inhibitors of the essential nematode-specific metalloprotease DPY-31.

PubMed

France, David J; Stepek, Gillian; Houston, Douglas R; Williams, Lewis; McCormack, Gillian; Walkinshaw, Malcolm D; Page, Antony P

2015-12-15

Infection by parasitic nematodes is widespread in the developing world causing extensive morbidity and mortality. Furthermore, infection of animals is a global problem, with a substantial impact on food production. Here we identify small molecule inhibitors of a nematode-specific metalloprotease, DPY-31, using both known metalloprotease inhibitors and virtual screening. This strategy successfully identified several μM inhibitors of DPY-31 from both the human filarial nematode Brugia malayi, and the parasitic gastrointestinal nematode of sheep Teladorsagia circumcincta. Further studies using both free living and parasitic nematodes show that these inhibitors elicit the severe body morphology defect 'Dumpy' (Dpy; shorter and fatter), a predominantly non-viable phenotype consistent with mutants lacking the DPY-31 gene. Taken together, these results represent a start point in developing DPY-31 inhibition as a totally novel mechanism for treating infection by parasitic nematodes in humans and animals. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

AMF-induced biocontrol against plant parasitic nematodes in Musa sp.: a systemic effect.

PubMed

Elsen, A; Gervacio, D; Swennen, R; De Waele, D

2008-07-01

Although mycorrhizal colonization provides a bioprotectional effect against a broad range of soil-borne pathogens, including plant parasitic nematodes, the commercial use of arbuscular mycorrhizal fungi (AMF) as biocontrol agents is still in its infancy. One of the main reasons is the poor understanding of the modes of action. Most AMF mode of action studies focused on AMF-bacterial/fungal pathogens. Only few studies so far examined AMF-plant parasitic nematode interactions. Therefore, the aim of the study was to determine whether the AMF Glomus intraradices was able to incite systemic resistance in banana plants towards Radopholus similis and Pratylenchus coffeae, two plant parasitic nematodes using a split-root compartmental set-up. The AMF reduced both nematode species by more than 50%, even when the AMF and the plant parasitic nematodes were spatially separated. The results obtained demonstrate for the first time that AMF have the ability to induce systemic resistance against plant parasitic nematodes in a root system.

Nematode assemblages in the deep-sea benthos of the Norwegian Sea

NASA Astrophysics Data System (ADS)

Jensen, Preben

1988-07-01

The deep-sea benthos of the Norwegian Sea contains 20-204 nematodes per 10 cm 2 down to 3 cm depth at seven stations sampled between 970 and 3294 m water depth. The majority of nematodes occur in the uppermost cm. Biomass varies from 3 to 73 μg C per 10 cm 2. Individual adult weight of the most dominant species differs by a factor of almost 1000, i.e. from 3-4 ng C to 3400 ng C; however, the majority of the nematodes is small-sized. Species diversity and evenness are high at all stations and each station harbours its specific fauna with little overlap between stations. Analysis of trophic group composition suggests that microbial feeding types (deposit and epistrate feeders) prevail in the deep-sea benthos; predators and scavengers are scarce. It is concluded that the nematode assemblage at each station consists of a mosaic of many microhabitats. The small nematode body weight probably results from limited food supply and/or poor food quality.

Optimization of a Host Diet for in vivo Production of Entomopathogenic Nematodes

PubMed Central

Shapiro-Ilan, David; Guadalupe Rojas, M.; Morales-Ramos, Juan A.; Louis Tedders, W.

2012-01-01

To facilitate improved in vivo culture of entomopathogenic nematodes, production of both insect hosts and nematodes should be optimized for maximum fitness, quality, and cost efficiency. In previous studies, we developed an improved diet for Tenebrio molitor, a host that is used for in vivo nematode production, and we demonstrated that single insect diet components (e.g., lipids and proteins) can have a positive or negative impact on entomopathogenic nematode fitness and quality. In this study, we tested components of our improved T. molitor diet (lipids, cholesterol, and a salt [MnSO4]) alone and in combination for effects on host susceptibility and reproductive capacity of Heterorhabditis indica and Steinernema carpocapsae. Our results indicated that moderate levels of lipids (10%) increased host susceptibility to S. carpocapsae but did not affect H. indica, whereas cholesterol and MnSO4 increased host susceptibility to H. indica but not S. carpocapsae. The combined T. molitor diet (improved for increased insect growth) increased host susceptibility to S. carpocapsae and had a neutral effect on H. indica; interactions among single diet ingredients were observed. No effects of insect host diet were detected on the reproductive capacity of either nematode species in T. molitor. Subsequently, progeny infective juveniles, derived from nematodes grown in T. molitor that were fed diets with varying nutritive components were tested for virulence to and reproduction capacity in the target pest Diaprepes abbreviatus. The progeny nematodes produced from differing T. molitor diet treatments did not differ in virulence except H. indica derived from a diet that lacked cholesterol or MnS04 (but contained lipids) did not cause significant D. abbreviatus suppression relative to the water control. We conclude that the improved insect host diet is compatible with production of H. indica and S. carpocapsae, and increases host susceptibility in S. carpocapsae. Furthermore, in a

Nematode Spatial and Ecological Patterns from Tropical and Temperate Rainforests

PubMed Central

Porazinska, Dorota L.; Giblin-Davis, Robin M.; Powers, Thomas O.; Thomas, W. Kelley

2012-01-01

Large scale diversity patterns are well established for terrestrial macrobiota (e.g. plants and vertebrates), but not for microscopic organisms (e.g. nematodes). Due to small size, high abundance, and extensive dispersal, microbiota are assumed to exhibit cosmopolitan distributions with no biogeographical patterns. This assumption has been extrapolated from local spatial scale studies of a few taxonomic groups utilizing morphological approaches. Recent molecularly-based studies, however, suggest something quite opposite. Nematodes are the most abundant metazoans on earth, but their diversity patterns are largely unknown. We conducted a survey of nematode diversity within three vertical strata (soil, litter, and canopy) of rainforests at two contrasting latitudes in the North American meridian (temperate: the Olympic National Forest, WA, U.S.A and tropical: La Selva Biological Station, Costa Rica) using standardized sampling designs and sample processing protocols. To describe nematode diversity, we applied an ecometagenetic approach using 454 pyrosequencing. We observed that: 1) nematode communities were unique without even a single common species between the two rainforests, 2) nematode communities were unique among habitats in both rainforests, 3) total species richness was 300% more in the tropical than in the temperate rainforest, 4) 80% of the species in the temperate rainforest resided in the soil, whereas only 20% in the tropics, 5) more than 90% of identified species were novel. Overall, our data provided no support for cosmopolitanism at both local (habitats) and large (rainforests) spatial scales. In addition, our data indicated that biogeographical patterns typical of macrobiota also exist for microbiota. PMID:22984536

Communities of terrestrial nematodes after different approaches to heathland restoration

NASA Astrophysics Data System (ADS)

Radochova, Petra; Frouz, Jan

2016-04-01

Since the 20th century, the distribution of European heathlands rapidly decreased due to agricultural intensification, heavy use of artificial fertilizers or acidification (Aerts & Heil, 1993). Therefore, various attempts of heathland restoration are under way in these days. Analysis of nematode community composition can be one of the tools suitable for succession evaluation (Ferris et al., 2001). In 2011, 2013 and 2014, soil samples were collected from heathland restoration experiment (launched in 2011) where different restoration methods were applied in a 3 × 3 factorial experiment; existing heathlands were also sampled to identify the target community both in dry and wet heathland. A total of 60 samples of extracted nematodes were analysed for absolute abundance, trophic groups, and genera dominance. Various indices were calculated to describe the nematode community. We were able to prove faster development of wet heathlands towards the target community. However, because of large data variability, there was no significant difference between treatments. Development of wet and dry heathlands differed also in increased proportion of omniphagous nematodes in 2013 and predators in 2014 in dry heathlands. After three years of heathland restoration, nematode community has not yet reached parameters of the target community. References Aerts, R., Heil, G. W., 1993. Heathlands: patterns and processes in a changing environment, 1st ed, Geobotany: 20. Springer Netherlands, Dordrecht, p. 229. Ferris, H., Bongers, T., De Goede, R. G. M., 2001. A framework for soil food web diagnostics: Extension of the nematode faunal analysis oncept. Appl. Soil Ecol. 18, 13-29.

flp-32 Ligand/receptor silencing phenocopy faster plant pathogenic nematodes.

PubMed

Atkinson, Louise E; Stevenson, Michael; McCoy, Ciaran J; Marks, Nikki J; Fleming, Colin; Zamanian, Mostafa; Day, Tim A; Kimber, Michael J; Maule, Aaron G; Mousley, Angela

2013-02-01

Restrictions on nematicide usage underscore the need for novel control strategies for plant pathogenic nematodes such as Globodera pallida (potato cyst nematode) that impose a significant economic burden on plant cultivation activities. The nematode neuropeptide signalling system is an attractive resource for novel control targets as it plays a critical role in sensory and motor functions. The FMRFamide-like peptides (FLPs) form the largest and most diverse family of neuropeptides in invertebrates, and are structurally conserved across nematode species, highlighting the utility of the FLPergic system as a broad-spectrum control target. flp-32 is expressed widely across nematode species. This study investigates the role of flp-32 in G. pallida and shows that: (i) Gp-flp-32 encodes the peptide AMRNALVRFamide; (ii) Gp-flp-32 is expressed in the brain and ventral nerve cord of G. pallida; (iii) migration rate increases in Gp-flp-32-silenced worms; (iv) the ability of G. pallida to infect potato plant root systems is enhanced in Gp-flp-32-silenced worms; (v) a novel putative Gp-flp-32 receptor (Gp-flp-32R) is expressed in G. pallida; and, (vi) Gp-flp-32R-silenced worms also display an increase in migration rate. This work demonstrates that Gp-flp-32 plays an intrinsic role in the modulation of locomotory behaviour in G. pallida and putatively interacts with at least one novel G-protein coupled receptor (Gp-flp-32R). This is the first functional characterisation of a parasitic nematode FLP-GPCR.

Benthic-Pelagic Coupling: Effects on Nematode Communities along Southern European Continental Margins

PubMed Central

Pape, Ellen; Jones, Daniel O. B.; Manini, Elena; Bezerra, Tania Nara; Vanreusel, Ann

2013-01-01

Along a west-to-east axis spanning the Galicia Bank region (Iberian margin) and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m). Nematode standing stock (abundance and biomass) and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude) governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter). Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes. PMID:23565176

Profiling Nematode Communities in Unmanaged Flowerbed and Agricultural Field Soils in Japan by DNA Barcode Sequencing

PubMed Central

Morise, Hisashi; Miyazaki, Erika; Yoshimitsu, Shoko; Eki, Toshihiko

2012-01-01

Soil nematodes play crucial roles in the soil food web and are a suitable indicator for assessing soil environments and ecosystems. Previous nematode community analyses based on nematode morphology classification have been shown to be useful for assessing various soil environments. Here we have conducted DNA barcode analysis for soil nematode community analyses in Japanese soils. We isolated nematodes from two different environmental soils of an unmanaged flowerbed and an agricultural field using the improved flotation-sieving method. Small subunit (SSU) rDNA fragments were directly amplified from each of 68 (flowerbed samples) and 48 (field samples) isolated nematodes to determine the nucleotide sequence. Sixteen and thirteen operational taxonomic units (OTUs) were obtained by multiple sequence alignment from the flowerbed and agricultural field nematodes, respectively. All 29 SSU rDNA-derived OTUs (rOTUs) were further mapped onto a phylogenetic tree with 107 known nematode species. Interestingly, the two nematode communities examined were clearly distinct from each other in terms of trophic groups: Animal predators and plant feeders were markedly abundant in the flowerbed soils, in contrast, bacterial feeders were dominantly observed in the agricultural field soils. The data from the flowerbed nematodes suggests a possible food web among two different trophic nematode groups and plants (weeds) in the closed soil environment. Finally, DNA sequences derived from the mitochondrial cytochrome oxidase c subunit 1 (COI) gene were determined as a DNA barcode from 43 agricultural field soil nematodes. These nematodes were assigned to 13 rDNA-derived OTUs, but in the COI gene analysis were assigned to 23 COI gene-derived OTUs (cOTUs), indicating that COI gene-based barcoding may provide higher taxonomic resolution than conventional SSU rDNA-barcoding in soil nematode community analysis. PMID:23284767

Conserved nematode signaling molecules elicit plant defenses and pathogen resistance

USDA-ARS?s Scientific Manuscript database

Nematodes, which are ubiquitous in soil and are estimated to cause $100 B of agricultural damage annually, produce novel, highly conserved small sugar-based molecules call ascarosides. Ascarosides play critical roles in nematode development and behavior. We report here that plants recognize these un...

Parasitic nematodes modulate PIN-mediated auxin transport to facilitate infection.

PubMed

Grunewald, Wim; Cannoot, Bernard; Friml, Jirí; Gheysen, Godelieve

2009-01-01

Plant-parasitic nematodes are destructive plant pathogens that cause significant yield losses. They induce highly specialized feeding sites (NFS) in infected plant roots from which they withdraw nutrients. In order to establish these NFS, it is thought that the nematodes manipulate the molecular and physiological pathways of their hosts. Evidence is accumulating that the plant signalling molecule auxin is involved in the initiation and development of the feeding sites of sedentary plant-parasitic nematodes. Intercellular transport of auxin is essential for various aspects of plant growth and development. Here, we analysed the spatial and temporal expression of PIN auxin transporters during the early events of NFS establishment using promoter-GUS/GFP fusion lines. Additionally, single and double pin mutants were used in infection studies to analyse the role of the different PIN proteins during cyst nematode infection. Based on our results, we postulate a model in which PIN1-mediated auxin transport is needed to deliver auxin to the initial syncytial cell, whereas PIN3 and PIN4 distribute the accumulated auxin laterally and are involved in the radial expansion of the NFS. Our data demonstrate that cyst nematodes are able to hijack the auxin distribution network in order to facilitate the infection process.

Contrasting diversity patterns of soil mites and nematodes in secondary succession

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kardol, Paul; Newton, Jeffrey S.; Bezemer, T Martijn

2009-01-01

Soil biodiversity has been recognized as a key feature of ecosystem functioning and stability. However, soil biodiversity is strongly impaired by agriculture and relatively little is known on how and at what spatial and temporal scales soil biodiversity is restored after the human disturbances have come to an end. Here, a multi-scale approach was used to compare diversity patterns of soil mites and nematodes at four stages (early, mid, late, reference site) along a secondary succession chronosequence from abandoned arable land to heath land. In each field four soil samples were taken during four successive seasons. We determined soil diversitymore » within samples ({alpha}-diversity), between samples ({beta}-diversity) and within field sites ({gamma}-diversity). The patterns of {alpha}- and {gamma}-diversity developed similarly along the chronosequence for oribatid mites, but not for nematodes. Nematode {alpha}-diversity was highest in mid- and late-successional sites, while {gamma}-diversity was constant along the chronosequence. Oribatid mite {beta}-diversity was initially high, but decreased thereafter, whereas nematode {beta}-diversity increased when succession proceeded; indicating that patterns of within-site heterogeneity diverged for oribatid mites and nematodes. The spatio-temporal diversity patterns after land abandonment suggest that oribatid mite community development depends predominantly on colonization of new taxa, whereas nematode community development depends on shifts in dominance patterns. This would imply that at old fields diversity patterns of oribatid mites are mainly controlled by dispersal, whereas diversity patterns of nematodes are mainly controlled by changing abiotic or biotic soil conditions. Our study shows that the restoration of soil biodiversity along secondary successional gradients can be both scale- and phylum-dependent.« less

Secretome Analysis of the Pine Wood Nematode Bursaphelenchus xylophilus Reveals the Tangled Roots of Parasitism and Its Potential for Molecular Mimicry

PubMed Central

Shinya, Ryoji; Takeuchi, Yuko; Ueda, Mitsuyoshi; Futai, Kazuyoshi

2013-01-01

Since it was first introduced into Asia from North America in the early 20th century, the pine wood nematode Bursaphelenchus xylophilus has caused the devastating forest disease called pine wilt. The emerging pathogen spread to parts of Europe and has since been found as the causal agent of pine wilt disease in Portugal and Spain. In 2011, the entire genome sequence of B. xylophilus was determined, and it allowed us to perform a more detailed analysis of B. xylophilus parasitism. Here, we identified 1,515 proteins secreted by B. xylophilus using a highly sensitive proteomics method combined with the available genomic sequence. The catalogue of secreted proteins contained proteins involved in nutrient uptake, migration, and evasion from host defenses. A comparative functional analysis of the secretome profiles among parasitic nematodes revealed a marked expansion of secreted peptidases and peptidase inhibitors in B. xylophilus via gene duplication and horizontal gene transfer from fungi and bacteria. Furthermore, we showed that B. xylophilus secreted the potential host mimicry proteins that closely resemble the host pine’s proteins. These proteins could have been acquired by host–parasite co-evolution and might mimic the host defense systems in susceptible pine trees during infection. This study contributes to an understanding of their unique parasitism and its tangled roots, and provides new perspectives on the evolution of plant parasitism among nematodes. PMID:23805310

Secretome Analysis of the Pine Wood Nematode Bursaphelenchus xylophilus Reveals the Tangled Roots of Parasitism and Its Potential for Molecular Mimicry.

PubMed

Shinya, Ryoji; Morisaka, Hironobu; Kikuchi, Taisei; Takeuchi, Yuko; Ueda, Mitsuyoshi; Futai, Kazuyoshi

2013-01-01

Since it was first introduced into Asia from North America in the early 20(th) century, the pine wood nematode Bursaphelenchus xylophilus has caused the devastating forest disease called pine wilt. The emerging pathogen spread to parts of Europe and has since been found as the causal agent of pine wilt disease in Portugal and Spain. In 2011, the entire genome sequence of B. xylophilus was determined, and it allowed us to perform a more detailed analysis of B. xylophilus parasitism. Here, we identified 1,515 proteins secreted by B. xylophilus using a highly sensitive proteomics method combined with the available genomic sequence. The catalogue of secreted proteins contained proteins involved in nutrient uptake, migration, and evasion from host defenses. A comparative functional analysis of the secretome profiles among parasitic nematodes revealed a marked expansion of secreted peptidases and peptidase inhibitors in B. xylophilus via gene duplication and horizontal gene transfer from fungi and bacteria. Furthermore, we showed that B. xylophilus secreted the potential host mimicry proteins that closely resemble the host pine's proteins. These proteins could have been acquired by host-parasite co-evolution and might mimic the host defense systems in susceptible pine trees during infection. This study contributes to an understanding of their unique parasitism and its tangled roots, and provides new perspectives on the evolution of plant parasitism among nematodes.

In vivo anthelmintic activity of Anogeissus leiocarpus Guill & Perr (Combretaceae) against nematodes in naturally infected sheep.

PubMed

Soro, Dramane; Koné, Witabouna Mamidou; Bonfoh, Bassirou; Dro, Bernadin; Toily, Kassédo Bénédicte; Kamanzi, Kagoyire

2013-07-01

The identification of new anthelmintic drugs becomes a priority because of the availability of a handful of drugs, cost of treatments, and recent emergence of drug resistance. Medicinal plants are a good source of bioactive compounds for development of drugs. In this study, in vivo efficacy of Anogeissus leiocarpus was assessed in sheep naturally infected with gastrointestinal nematodes. Fecal examination, serological analyses, and necropsy were carried out to determine the egg and worm-burden reduction. The administration of ethanolic extract (single oral dose of 80 mg/kg) of A. leiocarpus induced a moderate fecal egg reduction (81 %) and adult worm-burden reduction (87 %) against Haemonchus contortus and Trichostrongylus colubriformis (82 %). The plant exhibited high efficacy against adult Strongyloïdes papillosus (100 %), Gaigeria pachyscelis (90 %), Cooperia curticei (100 %), and Oesophagostomum columbianum (95 %) but low efficacy against Trichostrongylus axei (67 %) and Trichuris globulosa (79 %). All these helminthes were sensitive to fenbendazole, except O. columbianum which showed a decrease susceptibility (17 %). The plant extract also improved certain biological parameters by increasing bodyweight from 0.7 ± 2.9 to 3.3 ± 1.9 % and improving hematocrit of 6.9 ± 1.6 % 3-week posttreatment. It emerges from the results that the plant possesses significant effectiveness on diarrhea; all treated animals gave normal feces. This study has shown that A. leiocarpus could find an application in the control of multiparasitism in small ruminants.

Azadirachtin powder for control of root-knot nematodes in tomato

USDA-ARS?s Scientific Manuscript database

USDA ARS Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, 64 Nowelo St., Hilo, HI 96720. Root-knot nematodes cause root galling and yield reductions in many vegetable crops, including tomato. Three organic treatments to improve root growth and reduce nematode infestation were eval...

High Sensitivity NMR and Mixture Analysis for Nematode Behavioral Metabolomics

USDA-ARS?s Scientific Manuscript database

Nematodes are the most abundant animal on earth, and they parasitize virtually all plants and animals. Caenorhabditis elegans is a free-living nematode that lives in soil and composting material. We have shown that C. elegans releases at least 40 small molecules into its environment including many...

Potential Nematode Alarm Pheromone Induces Acute Avoidance in Caenorhabditis elegans.

PubMed

Zhou, Ying; Loeza-Cabrera, Mario; Liu, Zheng; Aleman-Meza, Boanerges; Nguyen, Julie K; Jung, Sang-Kyu; Choi, Yuna; Shou, Qingyao; Butcher, Rebecca A; Zhong, Weiwei

2017-07-01

It is crucial for animal survival to detect dangers such as predators. A good indicator of dangers is injury of conspecifics. Here we show that fluids released from injured conspecifics invoke acute avoidance in both free-living and parasitic nematodes. Caenorhabditis elegans avoids extracts from closely related nematode species but not fruit fly larvae. The worm extracts have no impact on animal lifespan, suggesting that the worm extract may function as an alarm instead of inflicting physical harm. Avoidance of the worm extract requires the function of a cGMP signaling pathway that includes the cGMP-gated channel TAX-2/TAX-4 in the amphid sensory neurons ASI and ASK. Genetic evidence indicates that the avoidance behavior is modulated by the neurotransmitters GABA and serotonin, two common targets of anxiolytic drugs. Together, these data support a model that nematodes use a nematode-specific alarm pheromone to detect conspecific injury. Copyright © 2017 by the Genetics Society of America.

Effect of nematodes on rhizosphere colonization by seed-applied bacteria.

PubMed

Knox, Oliver G G; Killham, Ken; Artz, Rebekka R E; Mullins, Chris; Wilson, Michael

2004-08-01

There is much interest in the use of seed-applied bacteria for biocontrol and biofertilization, and several commercial products are available. However, many attempts to use this strategy fail because the seed-applied bacteria do not colonize the rhizosphere. Mechanisms of rhizosphere colonization may involve active bacterial movement or passive transport by percolating water or plant roots. Transport by other soil biota is likely to occur, but this area has not been well studied. We hypothesized that interactions with soil nematodes may enhance colonization. To test this hypothesis, a series of microcosm experiments was carried out using two contrasting soils maintained under well-defined physical conditions where transport by mass water flow could not occur. Seed-applied Pseudomonas fluorescens SBW25 was capable of rhizosphere colonization at matric potentials of -10 and -40 kPa in soil without nematodes, but colonization levels were substantially increased by the presence of nematodes. Our results suggest that nematodes can have an important role in rhizosphere colonization by bacteria in soil.

Evaluation of anthelmintic activity of Iris hookeriana against gastrointestinal nematodes of sheep.

PubMed

Tariq, K A; Chishti, M Z; Ahmad, F; Shawl, A S; Tantray, M A

2008-06-01

The objective of this study was to evaluate the anthelmintic efficacy of Iris hookeriana Linn. rhizome against gastrointestinal nematodes of sheep. A worm motility inhibition assay was used for in vitro study and a faecal egg count reduction assay was used for an in vivo study. The in vitro study revealed anthelmintic effects of crude aqueous extracts and crude ethanolic extracts on live Trichuris ovis worms (P < or = 0.05) as evident from their paralysis and/or death at 8 h after exposure. The aqueous extracts of I. hookeriana resulted in a mean worm motility inhibition of 54.0%, while ethanolic extracts resulted in a mean worm motility inhibition of 84.6%. The mean mortality index of aqueous extracts was 0.55, while for ethanolic extracts it was 0.85. The lethal concentration 50 for aqueous extracts was 0.45 mg ml- 1 and for ethanolic extracts it was 0.15 mg ml- 1. The in vivo anthelmintic activity of aqueous and ethanolic extracts of I. hookeriana in sheep naturally infected with mixed species of gastrointestinal nematodes demonstrated a maximum (45.62%) egg count reduction in sheep treated with ethanolic extracts at 2 g kg- 1 body weight on day 10 after treatment, closely followed by ethanolic extracts at 1 g kg- 1 body weight on day 10 after treatment (43.54% egg count reduction). The aqueous extracts resulted in a maximum of 31.53% reduction in faecal egg counts on day 10 after treatment with 1 g kg- 1 body weight. Thus ethanolic extracts exhibited greater anthelmintic activity under both in vitro and in vivo conditions; this could be due to the presence of alcohol-soluble active ingredients in I. hookeriana. From the present study it can be suggested that I. hookeriana rhizome exhibited significant anthelmintic activity against gastrointestinal nematodes of sheep and has the potential to contribute to the control of gastrointestinal nematode parasites of small ruminants.

The effect of supplementary feeding on the resilience and resistance of browsing Criollo kids against natural gastrointestinal nematode infections during the rainy season in tropical Mexico.

PubMed

Torres-Acosta, J F J; Jacobs, D E; Aguilar-Caballero, A; Sandoval-Castro, C; May-Martinez, M; Cob-Galera, L A

2004-10-05

The objective was to determine the effect of supplementary feeding on the resilience and resistance of Criollo kids against natural gastrointestinal nematode (GIN) infections, when browsing native vegetation during the wet season in tropical Mexico. Thirty-four 2-month old Criollo kids, raised nematode free, were included at weaning in a 22-week trial. The kids were placed into four groups. Two groups of 8 kids were offered 100g/day soybean and sorghum meal (26%:74%, respectively fresh basis) (treated/supplemented (T-S) and infected/supplemented (I-S)). Two groups remained with no supplement for the duration of the trial (infected/non-supplemented (I-NS) (n = 10) and treated/non-supplemented (T-NS) (n = 8)). Kids in groups T-S and T-NS were drenched with 0.2mg of moxidectin/kg body weight orally (Cydectin, Fort Dodge) every 28 days. Groups I-S and I-NS were naturally infected with GIN. The animals browsed native vegetation (for an average of 7h/day) together with a herd of 120 naturally infected adult goats. Cumulative live weight gain (CLWG), packed cell volume (PCV), haemoglobin (Hb), total plasma protein and plasma albumin were recorded every 14 days as measurements of resilience. Resistance parameters (faecal egg counts (FEC) and peripheral eosinophil counts (PEC)) were also measured. Bulk faecal cultures were made for each group every 28 days. Every month a new pair of tracer kids assessed the infectivity of the vegetation browsed by the animals. The T-S group had the highest CLWG, PCV and Hb compared to the other three groups (P < 0.001). The I-S and T-NS group had similar mean CLWG and PCV (P > 0.05), while the I-NS group had the poorest CLWG, PCV and Hb (P < 0.001). The PEC of supplemented kids (I-S and T-S) was higher than in the I-NS and T-NS kids (P < 0.05). No effect of supplementary feeding was found in the FEC. Tracer kids and faecal cultures showed that kids suffered mixed infections with Haemonchus contortus, Trichostrongylus colubriformis and

Suppression of NGB and NAB/ERabp1 in tomato modifies root responses to potato cyst nematode infestation.

PubMed

Dąbrowska-Bronk, Joanna; Czarny, Magdalena; Wiśniewska, Anita; Fudali, Sylwia; Baranowski, Łukasz; Sobczak, Mirosław; Święcicka, Magdalena; Matuszkiewicz, Mateusz; Brzyżek, Grzegorz; Wroblewski, Tadeusz; Dobosz, Renata; Bartoszewski, Grzegorz; Filipecki, Marcin

2015-05-01

Plant-parasitic nematodes cause significant damage to major crops throughout the world. The small number of genes conferring natural plant resistance and the limitations of chemical control require the development of new protective strategies. RNA interference or the inducible over-expression of nematicidal genes provides an environment-friendly approach to this problem. Candidate genes include NGB, which encodes a small GTP-binding protein, and NAB/ERabp1, which encodes an auxin-binding protein, which were identified as being up-regulated in tomato roots in a transcriptome screen of potato cyst nematode (Globodera rostochiensis) feeding sites. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization confirmed the localized up-regulation of these genes in syncytia and surrounding cells following nematode infection. Gene-silencing constructs were introduced into tomato, resulting in a 20%-98% decrease in transcription levels. Nematode infection tests conducted on transgenic plants showed 57%-82% reduction in the number of G. rostochiensis females in vitro and 30%-46% reduction in pot trials. Transmission electron microscopy revealed a deterioration of cytoplasm, and degraded mitochondria and plastids, in syncytia induced in plants with reduced NAB/ERabp1 expression. Cytoplasm in syncytia induced in plants with low NGB expression was strongly electron translucent and contained very few ribosomes; however, mitochondria and plastids remained intact. Functional impairments in syncytial cytoplasm of silenced plants may result from NGB's role in ribosome biogenesis; this was confirmed by localization of yellow fluorescent protein (YFP)-labelled NGB protein in nucleoli and co-repression of NGB in plants with reduced NAB/ERabp1 expression. These results demonstrate that NGB and NAB/ERabp1 play important roles in the development of nematode-induced syncytia. © 2014 BSPP AND JOHN WILEY & SONS LTD.

Daytime warming has stronger negative effects on soil nematodes than night-time warming.

PubMed

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-07

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Daytime warming has stronger negative effects on soil nematodes than night-time warming.

PubMed

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-20

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Daytime warming has stronger negative effects on soil nematodes than night-time warming

PubMed Central

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-01-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming. PMID:28317914

Daytime warming has stronger negative effects on soil nematodes than night-time warming

NASA Astrophysics Data System (ADS)

Yan, Xiumin; Wang, Kehong; Song, Lihong; Wang, Xuefeng; Wu, Donghui

2017-03-01

Warming of the climate system is unequivocal, that is, stronger warming during night-time than during daytime. Here we focus on how soil nematodes respond to the current asymmetric warming. A field infrared heating experiment was performed in the western of the Songnen Plain, Northeast China. Three warming modes, i.e. daytime warming, night-time warming and diurnal warming, were taken to perform the asymmetric warming condition. Our results showed that the daytime and diurnal warming treatment significantly decreased soil nematodes density, and night-time warming treatment marginally affected the density. The response of bacterivorous nematode and fungivorous nematode to experimental warming showed the same trend with the total density. Redundancy analysis revealed an opposite effect of soil moisture and soil temperature, and the most important of soil moisture and temperature in night-time among the measured environment factors, affecting soil nematode community. Our findings suggested that daily minimum temperature and warming induced drying are most important factors affecting soil nematode community under the current global asymmetric warming.

Mechanisms Involved in Nematode Control by Endophytic Fungi.

PubMed

Schouten, Alexander

2016-08-04

Colonization of plants by particular endophytic fungi can provide plants with improved defenses toward nematodes. Evidently, such endophytes can be important in developing more sustainable agricultural practices. The mechanisms playing a role in this quantitative antagonism are poorly understood but most likely multifactorial. This knowledge gap obstructs the progress regarding the development of endophytes or endophyte-derived constituents into biocontrol agents. In part, this may be caused by the fact that endophytic fungi form a rather heterogeneous group. By combining the knowledge of the currently characterized antagonistic endophytic fungi and their effects on nematode behavior and biology with the knowledge of microbial competition and induced plant defenses, the various mechanisms by which this nematode antagonism operates or may operate are discussed. Now that new technologies are becoming available and more accessible, the currently unresolved mechanisms can be studied in greater detail than ever before.

Small-molecule pheromones and hormones controlling nematode development.

PubMed

Butcher, Rebecca A

2017-05-17

The existence of small-molecule signals that influence development in Caenorhabditis elegans has been known for several decades, but only in recent years have the chemical structures of several of these signals been established. The identification of these signals has enabled connections to be made between these small molecules and fundamental signaling pathways in C. elegans that influence not only development but also metabolism, fertility, and lifespan. Spurred by these important discoveries and aided by recent advances in comparative metabolomics and NMR spectroscopy, the field of nematode chemistry has the potential to expand dramatically in the coming years. This Perspective will focus on small-molecule pheromones and hormones that influence developmental events in the nematode life cycle (ascarosides, dafachronic acids, and nemamides), will cover more recent work regarding the biosynthesis of these signals, and will explore how the discovery of these signals is transforming our understanding of nematode development and physiology.

Breeding for resistance to gastrointestinal nematodes - the potential in low-input/output small ruminant production systems.

PubMed

Zvinorova, P I; Halimani, T E; Muchadeyi, F C; Matika, O; Riggio, V; Dzama, K

2016-07-30

The control of gastrointestinal nematodes (GIN) is mainly based on the use of drugs, grazing management, use of copper oxide wire particles and bioactive forages. Resistance to anthelmintic drugs in small ruminants is documented worldwide. Host genetic resistance to parasites, has been increasingly used as a complementary control strategy, along with the conventional intervention methods mentioned above. Genetic diversity in resistance to GIN has been well studied in experimental and commercial flocks in temperate climates and more developed economies. However, there are very few report outputs from the more extensive low-input/output smallholder systems in developing and emerging countries. Furthermore, results on quantitative trait loci (QTL) associated with nematode resistance from various studies have not always been consistent, mainly due to the different nematodes studied, different host breeds, ages, climates, natural infections versus artificial challenges, infection level at sampling periods, among others. The increasing use of genetic markers (Single Nucleotide Polymorphisms, SNPs) in GWAS or the use of whole genome sequence data and a plethora of analytic methods offer the potential to identify loci or regions associated nematode resistance. Genomic selection as a genome-wide level method overcomes the need to identify candidate genes. Benefits in genomic selection are now being realised in dairy cattle and sheep under commercial settings in the more advanced countries. However, despite the commercial benefits of using these tools, there are practical problems associated with incorporating the use of marker-assisted selection or genomic selection in low-input/output smallholder farming systems breeding schemes. Unlike anthelmintic resistance, there is no empirical evidence suggesting that nematodes will evolve rapidly in response to resistant hosts. The strategy of nematode control has evolved to a more practical manipulation of host-parasite equilibrium

Exosomes secreted by nematode parasites transfer small RNAs to mammalian cells and modulate innate immunity.

PubMed

Buck, Amy H; Coakley, Gillian; Simbari, Fabio; McSorley, Henry J; Quintana, Juan F; Le Bihan, Thierry; Kumar, Sujai; Abreu-Goodger, Cei; Lear, Marissa; Harcus, Yvonne; Ceroni, Alessandro; Babayan, Simon A; Blaxter, Mark; Ivens, Alasdair; Maizels, Rick M

2014-11-25

In mammalian systems RNA can move between cells via vesicles. Here we demonstrate that the gastrointestinal nematode Heligmosomoides polygyrus, which infects mice, secretes vesicles containing microRNAs (miRNAs) and Y RNAs as well as a nematode Argonaute protein. These vesicles are of intestinal origin and are enriched for homologues of mammalian exosome proteins. Administration of the nematode exosomes to mice suppresses Type 2 innate responses and eosinophilia induced by the allergen Alternaria. Microarray analysis of mouse cells incubated with nematode exosomes in vitro identifies Il33r and Dusp1 as suppressed genes, and Dusp1 can be repressed by nematode miRNAs based on a reporter assay. We further identify miRNAs from the filarial nematode Litomosoides sigmodontis in the serum of infected mice, suggesting that miRNA secretion into host tissues is conserved among parasitic nematodes. These results reveal exosomes as another mechanism by which helminths manipulate their hosts and provide a mechanistic framework for RNA transfer between animal species.

Exosomes secreted by nematode parasites transfer small RNAs to mammalian cells and modulate innate immunity

PubMed Central

Buck, Amy H.; Coakley, Gillian; Simbari, Fabio; McSorley, Henry J.; Quintana, Juan F.; Le Bihan, Thierry; Kumar, Sujai; Abreu-Goodger, Cei; Lear, Marissa; Harcus, Yvonne; Ceroni, Alessandro; Babayan, Simon A.; Blaxter, Mark; Ivens, Alasdair; Maizels, Rick M.

2014-01-01

In mammalian systems RNA can move between cells via vesicles. Here we demonstrate that the gastrointestinal nematode Heligmosomoides polygyrus, which infects mice, secretes vesicles containing microRNAs (miRNAs) and Y RNAs as well as a nematode Argonaute protein. These vesicles are of intestinal origin and are enriched for homologues of mammalian exosome proteins. Administration of the nematode exosomes to mice suppresses Type 2 innate responses and eosinophilia induced by the allergen Alternaria. Microarray analysis of mouse cells incubated with nematode exosomes in vitro identifies Il33r and Dusp1 as suppressed genes, and Dusp1 can be repressed by nematode miRNAs based on a reporter assay. We further identify miRNAs from the filarial nematode Litomosoides sigmodontis in the serum of infected mice, suggesting that miRNA secretion into host tissues is conserved among parasitic nematodes. These results reveal exosomes as another mechanism by which helminths manipulate their hosts and provide a mechanistic framework for RNA transfer between animal species. PMID:25421927

Soil Nematode Responses to Increases in Nitrogen Deposition and Precipitation in a Temperate Forest

PubMed Central

Sun, Xiaoming; Zhang, Xiaoke; Zhang, Shixiu; Dai, Guanhua; Han, Shijie; Liang, Wenju

2013-01-01

The environmental changes arising from nitrogen (N) deposition and precipitation influence soil ecological processes in forest ecosystems. However, the corresponding effects of environmental changes on soil biota are poorly known. Soil nematodes are the important bioindicator of soil environmental change, and their responses play a key role in the feedbacks of terrestrial ecosystems to climate change. Therefore, to explore the responsive mechanisms of soil biota to N deposition and precipitation, soil nematode communities were studied after 3 years of environmental changes by water and/or N addition in a temperate forest of Changbai Mountain, Northeast China. The results showed that water combined with N addition treatment decreased the total nematode abundance in the organic horizon (O), while the opposite trend was found in the mineral horizon (A). Significant reductions in the abundances of fungivores, plant-parasites and omnivores-predators were also found in the water combined with N addition treatment. The significant effect of water interacted with N on the total nematode abundance and trophic groups indicated that the impacts of N on soil nematode communities were mediated by water availability. The synergistic effect of precipitation and N deposition on soil nematode communities was stronger than each effect alone. Structural equation modeling suggested water and N additions had direct effects on soil nematode communities. The feedback of soil nematodes to water and nitrogen addition was highly sensitive and our results indicate that minimal variations in soil properties such as those caused by climate changes can lead to severe changes in soil nematode communities. PMID:24324794

Analysis of Nematode Motion Using an Improved Light-Scatter Based System

PubMed Central

Nutting, Chuck S.; Eversole, Rob R.; Blair, Kevin; Specht, Sabine; Nutman, Thomas B.; Klion, Amy D.; Wanji, Samuel; Boussinesq, Michel; Mackenzie, Charles D.

2015-01-01

Background The detailed assessment of nematode activity and viability still remains a relatively undeveloped area of biological and medical research. Computer-based approaches to assessing the motility of larger nematode stages have been developed, yet these lack the capability to detect and analyze the more subtle and important characteristics of the motion of nematodes. There is currently a need to improved methods of assessing the viability and health of parasitic worms. Methods We describe here a system that converts the motion of nematodes through a light-scattering system into an electrical waveform, and allows for reproducible, and wholly non-subjective, assessment of alterations in motion, as well as estimation of the number of nematode worms of different forms and sizes. Here we have used Brugia sp. microfilariae (L1), infective larvae (L3) and adults, together with the free-living nematode Caenorhabditis elegans. Results The motion of worms in a small (200ul) volume can be detected, with the presence of immotile worms not interfering with the readings at practical levels (up to at least 500 L1 /200ul). Alterations in the frequency of parasite movement following the application of the anti-parasitic drugs, (chloroquine and imatinib); the anti-filarial effect of the latter agent is the first demonstrated here for the first time. This system can also be used to estimate the number of parasites, and shortens the time required to estimate parasites numbers, and eliminates the need for microscopes and trained technicians to provide an estimate of microfilarial sample sizes up to 1000 parasites/ml. Alterations in the form of motion of the worms can also be depicted. Conclusions This new instrument, named a "WiggleTron", offers exciting opportunities to further study nematode biology and to aid drug discovery, as well as contributing to a rapid estimate of parasite numbers in various biological samples. PMID:25695776

Analysis of nematode motion using an improved light-scatter based system.

PubMed

Nutting, Chuck S; Eversole, Rob R; Blair, Kevin; Specht, Sabine; Nutman, Thomas B; Klion, Amy D; Wanji, Samuel; Boussinesq, Michel; Mackenzie, Charles D

2015-02-01

The detailed assessment of nematode activity and viability still remains a relatively undeveloped area of biological and medical research. Computer-based approaches to assessing the motility of larger nematode stages have been developed, yet these lack the capability to detect and analyze the more subtle and important characteristics of the motion of nematodes. There is currently a need to improved methods of assessing the viability and health of parasitic worms. We describe here a system that converts the motion of nematodes through a light-scattering system into an electrical waveform, and allows for reproducible, and wholly non-subjective, assessment of alterations in motion, as well as estimation of the number of nematode worms of different forms and sizes. Here we have used Brugia sp. microfilariae (L1), infective larvae (L3) and adults, together with the free-living nematode Caenorhabditis elegans. The motion of worms in a small (200 ul) volume can be detected, with the presence of immotile worms not interfering with the readings at practical levels (up to at least 500 L1 /200 ul). Alterations in the frequency of parasite movement following the application of the anti-parasitic drugs, (chloroquine and imatinib); the anti-filarial effect of the latter agent is the first demonstrated here for the first time. This system can also be used to estimate the number of parasites, and shortens the time required to estimate parasites numbers, and eliminates the need for microscopes and trained technicians to provide an estimate of microfilarial sample sizes up to 1000 parasites/ml. Alterations in the form of motion of the worms can also be depicted. This new instrument, named a "WiggleTron", offers exciting opportunities to further study nematode biology and to aid drug discovery, as well as contributing to a rapid estimate of parasite numbers in various biological samples.

Entomopathogenic Nematodes Are Not an Alternative to Fenamiphos for Management of Plant-Parasitic Nematodes on Golf Courses in Florida

PubMed Central

Crow, WT; Porazinska, DL; Giblin-Davis, RM; Grewal, PS

2006-01-01

With the cancellation of fenamiphos in the near future, alternative nematode management tactics for plant-parasitic nematodes (PPN) on golf courses need to be identified. The use of entomopathogenic nematodes (EPN) has been suggested as one possible alternative. This paper presents the results of 10 experiments evaluating the efficacy of EPN at managing PPN on turfgrasses and improving turf performance. These experiments were conducted at various locations throughout Florida over the course of a decade. In different experiments, different EPN species were tested against different species of PPN. Separate experiments evaluated multiple rates and applications of EPN, compared different EPN species, and compared single EPN species against multiple species of PPN. In a few trials, EPN were associated with reductions in certain plant-parasite species, but in other trials were associated with increases. In most trials, EPN had no effect on plant parasites. Because EPN were so inconsistent in their results, we conclude that EPN are not acceptable alternatives to fenamiphos by most turf managers in Florida at this time. PMID:19259430

Analysis and functional classification of transcripts from the nematode Meloidogyne incognita

PubMed Central

McCarter, James P; Dautova Mitreva, Makedonka; Martin, John; Dante, Mike; Wylie, Todd; Rao, Uma; Pape, Deana; Bowers, Yvette; Theising, Brenda; Murphy, Claire V; Kloek, Andrew P; Chiapelli, Brandi J; Clifton, Sandra W; Bird, David Mck; Waterston, Robert H

2003-01-01

Background Plant parasitic nematodes are major pathogens of most crops. Molecular characterization of these species as well as the development of new techniques for control can benefit from genomic approaches. As an entrée to characterizing plant parasitic nematode genomes, we analyzed 5,700 expressed sequence tags (ESTs) from second-stage larvae (L2) of the root-knot nematode Meloidogyne incognita. Results From these, 1,625 EST clusters were formed and classified by function using the Gene Ontology (GO) hierarchy and the Kyoto KEGG database. L2 larvae, which represent the infective stage of the life cycle before plant invasion, express a diverse array of ligand-binding proteins and abundant cytoskeletal proteins. L2 are structurally similar to Caenorhabditis elegans dauer larva and the presence of transcripts encoding glyoxylate pathway enzymes in the M. incognita clusters suggests that root-knot nematode larvae metabolize lipid stores while in search of a host. Homology to other species was observed in 79% of translated cluster sequences, with the C. elegans genome providing more information than any other source. In addition to identifying putative nematode-specific and Tylenchida-specific genes, sequencing revealed previously uncharacterized horizontal gene transfer candidates in Meloidogyne with high identity to rhizobacterial genes including homologs of nodL acetyltransferase and novel cellulases. Conclusions With sequencing from plant parasitic nematodes accelerating, the approaches to transcript characterization described here can be applied to more extensive datasets and also provide a foundation for more complex genome analyses. PMID:12702207

HOW FUNGI INTERACT WITH NEMATODE TO ACTIVATE THE PLANT DEFENCE RESPONSE TO TOMATO PLANTS.

PubMed

Leonetti, P; Costanza, A; Zonno, M C; Molinari, S; Altomare, C

2014-01-01

Management of plant parasitic nematodes with nematode predators, parasites or antagonists is an eco-friendly approach that may avoid the problems arisen by the use of toxic chemicals. Fungi belonging to Trichoderma spp. are well known in literature for their role in control of plant parasitic nematodes. Root-knot nematodes (RKNs), Meloidogyne spp., are obligate parasites that cause the formation of familiar galls on the roots of many cultivated plants. The interaction between the M. incognita motile second stage juveniles (J2s) and the isolate ITEM 908 of Trichoderma harzianum was examined in its effect on the nematode infestation level of susceptible tomato plants. To gain insight into the mechanisms by which ITEM 908 interacts with nematode-infected tomato plants, the expression patterns of the genes PR1 (marker of Salycilic Acid-depending resistance signalling pathway) and JERF3 (marker of the Jasmonic Acid/Ethylene-depending resistance signalling pathway) were detected over time in: i) untreated roots; ii) roots pre-treated with the fungus; iii) roots inoculated with the nematode; iv) pre-treated and inoculated roots. Infestation parameters were checked in untreated plants and plants treated with the fungus to test the effect of the fungus on nematode infestation level and to compare this effect with the expression of the genes PR1 and JERF3, involved in induced resistance.

Control of Larval Northern Corn Rootworm. (Diabrotica barberi) with Two Steinernematid Nematode Species

PubMed Central

Thurston, G. S.; Yule, W. N.

1990-01-01

The entomogenous nematodes Steinerema feltiae and S. bibionis did not penetrate the roots of corn, Zea mays, to infect larval northern corn rootworm (NCR), Diabrotica barberi, feeding within. Laboratory bioassays against first instar NCR indicated that S. feltiae, Mexican strain (LD₅₀ = 49 nematodes/insect) is more virulent than S. bibionis (LD₅₀ = 100). Numbers of NCR larvae in a grain corn crop were reduced by both nematode species applied at corn seeding time at the rate of 10,000 infective-stage juveniles per linear meter of corn row. The chemical insecticide fonofos provided significantly better control than either nematode species. PMID:19287699

Nematode.net update 2011: addition of data sets and tools featuring next-generation sequencing data

PubMed Central

Martin, John; Abubucker, Sahar; Heizer, Esley; Taylor, Christina M.; Mitreva, Makedonka

2012-01-01

Nematode.net (http://nematode.net) has been a publicly available resource for studying nematodes for over a decade. In the past 3 years, we reorganized Nematode.net to provide more user-friendly navigation through the site, a necessity due to the explosion of data from next-generation sequencing platforms. Organism-centric portals containing dynamically generated data are available for over 56 different nematode species. Next-generation data has been added to the various data-mining portals hosted, including NemaBLAST and NemaBrowse. The NemaPath metabolic pathway viewer builds associations using KOs, rather than ECs to provide more accurate and fine-grained descriptions of proteins. Two new features for data analysis and comparative genomics have been added to the site. NemaSNP enables the user to perform population genetics studies in various nematode populations using next-generation sequencing data. HelmCoP (Helminth Control and Prevention) as an independent component of Nematode.net provides an integrated resource for storage, annotation and comparative genomics of helminth genomes to aid in learning more about nematode genomes, as well as drug, pesticide, vaccine and drug target discovery. With this update, Nematode.net will continue to realize its original goal to disseminate diverse bioinformatic data sets and provide analysis tools to the broad scientific community in a useful and user-friendly manner. PMID:22139919

Nematodes from terrestrial and freshwater habitats in the Arctic

PubMed Central

2014-01-01

Abstract We present an updated list of terrestrial and freshwater nematodes from all regions of the Arctic, for which records of properly identified nematode species are available: Svalbard, Jan Mayen, Iceland, Greenland, Nunavut, Northwest territories, Alaska, Lena River estuary, Taymyr and Severnaya Zemlya and Novaya Zemlya. The list includes 391 species belonging to 146 genera, 54 families and 10 orders of the phylum Nematoda. PMID:25197239

Natural parasitism of Metaparasitylenchus hypothenemi (Tylenchida: Allantonematidae) on the coffee berry borer, Hypothenemus hampei, in Chiapas, Mexico

USDA-ARS?s Scientific Manuscript database

Metaparasitylenchus hypothenemi is a relatively new nematode species found attacking the coffee berry borer, Hypothenemus hampei, in Mexico. We assessed the natural parasitism and distribution of this nematode in 20 coffee plantations in the state of Chiapas, at elevations ranging from 223 to 1458 m...

Novel bioassay demonstrates attraction of the white potato cyst nematode Globodera pallida (Stone) to non-volatile and volatile host plant cues.

PubMed

Farnier, Kevin; Bengtsson, Marie; Becher, Paul G; Witzell, Johanna; Witzgall, Peter; Manduríc, Sanja

2012-06-01

Potato cyst nematodes (PCNs) are a major pest of solanaceous crops such as potatoes, tomatoes, and eggplants and have been widely studied over the last 30 years, with the majority of earlier studies focusing on the identification of natural hatching factors. As a novel approach, we focused instead on chemicals involved in nematode orientation towards its host plant. A new dual choice sand bioassay was designed to study nematode responses to potato root exudates (PRE). This bioassay, conducted together with a traditional hatching bioassay, showed that biologically active compounds that induce both hatching and attraction of PCNs can be collected by water extraction of incised potato roots. Furthermore, our results demonstrated that PCN also were attracted by potato root volatiles. Further work is needed to fully understand how PCNs use host plant chemical cues to orientate towards hosts. Nevertheless, the simple attraction assay used in this study provides an important tool for the identification of host-emitted attractants.

The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes

PubMed Central

Danchin, Etienne G.J.; Perfus-Barbeoch, Laetitia; Rancurel, Corinne; Thorpe, Peter; Da Rocha, Martine; Bajew, Simon; Neilson, Roy; Sokolova (Guzeeva), Elena; Da Silva, Corinne; Guy, Julie; Labadie, Karine; Esmenjaud, Daniel; Helder, Johannes; Jones, John T.

2017-01-01

Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq) to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus, representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus, respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum. PMID:29065523

The Transcriptomes of Xiphinema index and Longidorus elongatus Suggest Independent Acquisition of Some Plant Parasitism Genes by Horizontal Gene Transfer in Early-Branching Nematodes.

PubMed

Danchin, Etienne G J; Perfus-Barbeoch, Laetitia; Rancurel, Corinne; Thorpe, Peter; Da Rocha, Martine; Bajew, Simon; Neilson, Roy; Guzeeva, Elena Sokolova; Da Silva, Corinne; Guy, Julie; Labadie, Karine; Esmenjaud, Daniel; Helder, Johannes; Jones, John T; den Akker, Sebastian Eves-van

2017-10-23

Nematodes have evolved the ability to parasitize plants on at least four independent occasions, with plant parasites present in Clades 1, 2, 10 and 12 of the phylum. In the case of Clades 10 and 12, horizontal gene transfer of plant cell wall degrading enzymes from bacteria and fungi has been implicated in the evolution of plant parasitism. We have used ribonucleic acid sequencing (RNAseq) to generate reference transcriptomes for two economically important nematode species, Xiphinema index and Longidorus elongatus , representative of two genera within the early-branching Clade 2 of the phylum Nematoda. We used a transcriptome-wide analysis to identify putative horizontal gene transfer events. This represents the first in-depth transcriptome analysis from any plant-parasitic nematode of this clade. For each species, we assembled ~30 million Illumina reads into a reference transcriptome. We identified 62 and 104 transcripts, from X. index and L. elongatus , respectively, that were putatively acquired via horizontal gene transfer. By cross-referencing horizontal gene transfer prediction with a phylum-wide analysis of Pfam domains, we identified Clade 2-specific events. Of these, a GH12 cellulase from X. index was analysed phylogenetically and biochemically, revealing a likely bacterial origin and canonical enzymatic function. Horizontal gene transfer was previously shown to be a phenomenon that has contributed to the evolution of plant parasitism among nematodes. Our findings underline the importance and the extensiveness of this phenomenon in the evolution of plant-parasitic life styles in this speciose and widespread animal phylum.

[Diversity of soil nematode communities in the subalpine and alpine forests of western Sichuan, China.

PubMed

Chen, Ya; Yang, Wan Qin; Wu, Fu Zhong; Yang, Fan; Lan, Li Ying; Liu, Yu Wei; Guo, Cai Hong; Tan, Bo

2017-10-01

In order to understand the diversity of soil nematodes in the subalpine/alpine forests of the eastern Qinghai-Tibet Plateau, soil nematodes in the primary forest, mixed forest and secondary forest of Abies faxoniana were extracted by elutriation and sugar-centrifugation method in July 2015, and the composition and structure characteristics of soil nematode communities were studied in the three forests at different altitudes. A total of 37950 soil nematodes were collected, which belonged to 20 families and 27 genera, and the mean density was 4217 ind·100 g -1 dry soil. Filenchus was the dominant genus in the primary forest, and Filenchus and Pararotylenchus in the mixed forest and secondary forest, respectively. The individual number of each dominant genus was significantly affected by forest type. All nematode individuals were classified into the four trophic groups of bacterivores, fungivores, plant-parasites and omnivore-predators. The fungivores were dominant in the primary and secondary forest and the bacterivores in the mixed forest. The number of soil nematode c-p (colonizer-persister) groups of c-p 1, c-p 2, c-p 3 and c-p 4 accounted for 6.1%, 51.1%, 30.0% and 12.7% of the total nematode abundance, respectively. The maturity index (MI), the total maturity index (∑MI) and the plant parasitic index (PPI) of soil nematodes decreased gradually with the increase of altitude. The nematode channel ratio in the mixed forest was higher than 0.5, but that in the primary forest and secondary forest was below 0.5. The forest type significantly affected the soil nematode maturity index and channel ratio, but the forest type, soil layer and their interaction had no significant effect on the diversity index. There were obvious diffe-rences in the composition, nutrient structure and energy flow channel of soil nematodes in the subalpine/alpine forests of western Sichuan, providing an important reference for understanding the function of soil nematodes in soil processes

Bioinformatic prediction of arthropod/nematode-like peptides in non-arthropod, non-nematode members of the Ecdysozoa.

PubMed

Christie, Andrew E; Nolan, Daniel H; Garcia, Zachery A; McCoole, Matthew D; Harmon, Sarah M; Congdon-Jones, Benjamin; Ohno, Paul; Hartline, Niko; Congdon, Clare Bates; Baer, Kevin N; Lenz, Petra H

2011-02-01

The Onychophora, Priapulida and Tardigrada, along with the Arthropoda, Nematoda and several other small phyla, form the superphylum Ecdysozoa. Numerous peptidomic studies have been undertaken for both the arthropods and nematodes, resulting in the identification of many peptides from each group. In contrast, little is known about the peptides used as paracrines/hormones by species from the other ecdysozoan taxa. Here, transcriptome mining and bioinformatic peptide prediction were used to identify peptides in members of the Onychophora, Priapulida and Tardigrada, the only non-arthropod, non-nematode members of the Ecdysozoa for which there are publicly accessible expressed sequence tags (ESTs). The extant ESTs for each phylum were queried using 106 arthropod/nematode peptide precursors. Transcripts encoding calcitonin-like diuretic hormone and pigment-dispersing hormone (PDH) were identified for the onychophoran Peripatopsis sedgwicki, with transcripts encoding C-type allatostatin (C-AST) and FMRFamide-like peptide identified for the priapulid Priapulus caudatus. For the Tardigrada, transcripts encoding members of the A-type allatostatin, C-AST, insect kinin, orcokinin, PDH and tachykinin-related peptide families were identified, all but one from Hypsibius dujardini (the exception being a Milnesium tardigradum orcokinin-encoding transcript). The proteins deduced from these ESTs resulted in the prediction of 48 novel peptides, six onychophoran, eight priapulid and 34 tardigrade, which are the first described from these phyla. Copyright © 2010 Elsevier Inc. All rights reserved.

Micro-electro-fluidic grids for nematodes: a lens-less, image-sensor-less approach for on-chip tracking of nematode locomotion.

PubMed

Liu, Peng; Martin, Richard J; Dong, Liang

2013-02-21

This paper reports on the development of a lens-less and image-sensor-less micro-electro-fluidic (MEF) approach for real-time monitoring of the locomotion of microscopic nematodes. The technology showed promise for overcoming the constraint of the limited field of view of conventional optical microscopy, with relatively low cost, good spatial resolution, and high portability. The core of the device was microelectrode grids formed by orthogonally arranging two identical arrays of microelectrode lines. The two microelectrode arrays were spaced by a microfluidic chamber containing a liquid medium of interest. As a nematode (e.g., Caenorhabditis elegans) moved inside the chamber, the invasion of part of its body into some intersection regions between the microelectrodes caused changes in the electrical resistance of these intersection regions. The worm's presence at, or absence from, a detection unit was determined by a comparison between the measured resistance variation of this unit and a pre-defined threshold resistance variation. An electronic readout circuit was designed to address all the detection units and read out their individual electrical resistances. By this means, it was possible to obtain the electrical resistance profile of the whole MEF grid, and thus, the physical pattern of the swimming nematode. We studied the influence of a worm's body on the resistance of an addressed unit. We also investigated how the full-frame scanning and readout rates of the electronic circuit and the dimensions of a detection unit posed an impact on the spatial resolution of the reconstructed images of the nematode. Other important issues, such as the manufacturing-induced initial non-uniformity of the grids and the electrotaxic behaviour of nematodes, were also studied. A drug resistance screening experiment was conducted by using the grids with a good resolution of 30 × 30 μm(2). The phenotypic differences in the locomotion behaviours (e.g., moving speed and oscillation

A novel ascaroside controls the parasitic life cycle of the entomopathogenic nematode Heterorhabditis bacteriophora.

PubMed

Noguez, Jaime H; Conner, Elizabeth S; Zhou, Yue; Ciche, Todd A; Ragains, Justin R; Butcher, Rebecca A

2012-06-15

Entomopathogenic nematodes survive in the soil as stress-resistant infective juveniles that seek out and infect insect hosts. Upon sensing internal host cues, the infective juveniles regurgitate bacterial pathogens from their gut that ultimately kill the host. Inside the host, the nematode develops into a reproductive adult and multiplies until unknown cues trigger the accumulation of infective juveniles. Here, we show that the entomopathogenic nematode Heterorhabditis bacteriophora uses a small-molecule pheromone to control infective juvenile development. The pheromone is structurally related to the dauer pheromone ascarosides that the free-living nematode Caenorhabditis elegans uses to control its development. However, none of the C. elegans ascarosides are effective in H. bacteriophora, suggesting that there is a high degree of species specificity. Our report is the first to show that ascarosides are important regulators of development in a parasitic nematode species. An understanding of chemical signaling in parasitic nematodes may enable the development of chemical tools to control these species.

Dose-response effects of clove oil from Syzygium aromaticum on the root-knot nematode Meloidogyne incognita.

PubMed

Meyer, Susan L F; Lakshman, Dilip K; Zasada, Inga A; Vinyard, Bryan T; Chitwood, David J

2008-03-01

Clove oil, derived from the plant Syzygium aromaticum (L.) Merr. & Perry, is active against various organisms, and was prepared in a soy lecithin/detergent formulation to determine concentrations active against the root-knot nematode Meloidogyne incognita (Kofoid and White) Chitwood. In microwell assays, the mean effective clove oil concentration that reduced egg hatch by 50% (EC(50)) was 0.097% (v/v) clove oil; the EC(50) for second-stage juvenile (J2) viability was 0.145% clove oil (compared with carrier control treatments). Volatiles from 5.0% clove oil reduced nematode egg hatch in water by 30%, and decreased viability of hatched J2 by as much as 100%. Reductions were not as large with nematodes in carrier. In soil trials with J2 recovered from Baermann funnels, the EC(50) = 0.192% clove oil (compared with water controls). The results demonstrated that the tested formulation is active against M. incognita eggs and J2, that the EC(50) values for J2 in the microwell studies and the soil recovery tests were similar to each other and that direct contact with the clove oil is needed for optimal management results with this natural product. (c) 2008 Society of Chemical Industry.

Role of nematode peptides and other small molecules in plant parasitism

USDA-ARS?s Scientific Manuscript database

Molecular, genetic, and biochemical studies are demonstrating an increasingly important role of peptide signaling in nematode parasitism of plants. To date, the majority of nematode-secreted peptides identified share similarity with plant CLAVATA3/ESR (CLE) peptides, but bioinformatics analyses of n...

A survival-reproduction trade-off in entomopathogenic nematodes mediated by their bacterial symbionts.

PubMed

Emelianoff, Vanya; Chapuis, Elodie; Le Brun, Nathalie; Chiral, Magali; Moulia, Catherine; Ferdy, Jean-Baptiste

2008-04-01

In this work, we investigate the investment of entomopathogenic Steinernema nematodes (Rhabditidae) in their symbiotic association with Xenorhabdus bacteria (Enterobacteriaceae). Their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (IJs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new IJs occur. Previous studies clearly showed benefits to the association for the nematode during the parasitic stage, but preliminary data suggest the existence of costs to the association for the nematode in free stage. IJs deprived from their bacteria indeed survive longer than symbiotic ones. Here we show that those bacteria-linked costs and benefits lead to a trade-off between fitness traits of the symbiotic nematodes. Indeed IJs mortality positively correlates with their parasitic success in the insect host for symbiotic IJs and not for aposymbiotic ones. Moreover mortality and parasitic success both positively correlate with the number of bacteria carried per IJ, indicating that the trade-off is induced by symbiosis. Finally, the trade-off intensity depends on parental effects and, more generally, is greater under restrictive environmental conditions.

Assessment of the behaviour and survival of nematodes under low oxygen concentrations

PubMed Central

Kitazume, Hiromi; Dayi, Mehmet; Tanaka, Ryusei

2018-01-01

Oxygen is required for the completion of almost all known metazoan lifecycles, but many metazoans harbour abilities to withstand varying degrees and periods of hypoxia. Caenorhabditis elegans, one of the most popular model organism is extensively used as a model for the study of hypoxia and anoxia biology and it has been found that this nematode is capable of tolerance to varying degrees of hypoxia. Considering the extremely high diversity of nematodes, the effects of low oxygen concentration and mechanisms of adaptation to oxygen depletion differ among species. In this study, we used a simple assay to examine anoxia tolerance in four nematode species, including three free-living and one plant parasitic nematode. We found that the plant parasitic nematode Bursaphelenchus xylophilus can survive more than 14 days under anoxic conditions. Comparisons of behaviour during anoxia induction and the repertoire of oxygen sensation genes among the tested species suggested the existence of different oxygen sensation systems between B. xylophilus and C. elegans, which quickly introduce suspended animation in response to oxygen depletion to survive long-term anoxia. PMID:29758056

Trophic position of soil nematodes in boreal forests as indicated by stable isotope analysis

NASA Astrophysics Data System (ADS)

Kudrin, Alexey; Tsurikov, Sergey

2016-04-01

Despite the well-developed trophic classification of soil nematodes, their position in soil food webs is still little understood. Observed deviations from the typical feeding strategy indicate that a simplified trophic classification probably does not fully reflect actual trophic interactions. Furthermore, the extent and functional significance of nematodes as prey for other soil animals remains unknown. Stable isotope analysis (SIA) is powerful tool for investigating the structure of soil food webs, but its application to the study of soil nematodes has been limited to only a few studies. We used stable isotope analysis to gain a better understanding of trophic links of several groups of soil nematodes in two boreal forests on albeluvisol. We investigated four taxonomic groups of nematodes: Mononchida, Dorylaimida, Plectidae and Tylenchidae (mostly from the genus Filenchus), that according to the conventional trophic classification represent predators, omnivores, bacterivores and root-fungal feeders, respectively. To assess the trophic position of nematodes, we used a comparison against a set of reference species including herbivorous, saprophagous and predatory macro-invertebrates, oribatid and mesostigmatid mites, and collembolans. Our results suggest that trophic position of the investigated groups of soil nematodes generally corresponds to the conventional classification. All nematodes were enriched in 13C relative to Picea abies roots and litter, and mycorrhizal fungal mycelium. Root-fungal feeders Tylenchidae had δ15N values similar to those of earthworms, enchytraeids and Entomobrya collembolans, but slightly lower δ13C values. Bacterivorous Plectidae were either equal or enriched in 15N compared with saprophagous macroinvertebrates and most mesofauna species. Omnivorous Dorylaimida and predatory Mononchida were further enriched in 15N and their isotopic signature was similar to that of predatory arthropods. These data confirm a clear separation of

Long-term effects of copper and pH on the nematode community in an agroecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korthals, G.W.; Lexmond, T.M.; Kammenga, J.E.

1996-06-01

Four copper (0, 250, 500, and 750 kg Cu-ha{sup {minus}1}) and pH (4.0, 4.7, 5.4, and 6.1 in 1 M KCl) treatments were applied to an arable agroecosystem., Effects on the nematode community were assessed after 10 years of exposure under field conditions. Both copper and pH had major influences on nematodes. The effect of copper was generally enhanced with decreasing soil pH. The lowest copper application rate which had a significant negative effect on the total number of nematodes was 250 kg{center_dot}ha{sup {minus}1} at pH 4.0, which is equivalent to a copper concentration of 0.32 mg{center_dot}L{sup {minus}1} in 0.01more » M calcium chloride (Cu-CaCl{sub 2}). Species composition and the abundance of trophic groups were more sensitive than the total number of nematodes. Combinations of high copper and low pH significantly reduced the number of bacterial-feeding nematodes, whereas the number of hyphal-feeding nematodes increased. Omnivorous and predacious nematodes showed the most sensitive response, becoming extinct when Cu-CaCl{sub 2} was 0.8 to 1.4 mg{center_dot}L{sup {minus}1}. Plant-feeding nematodes showed the largest differences in abundance and appeared to reflect the effects of copper and pH on primary production. The results suggest that the nematode community was also affected indirectly by copper and pH via other components of the soil food web. It is concluded that nematodes offer excellent perspectives to assess effects of pollutants at the community level.« less

The effect of different initial densities of nematode (Meloidogyne javanica) on the build-up of Pasteuria penetrans population.

PubMed

Darban, Daim Ali; Pathan, Mumtaz Ali; Bhatti, Abdul Ghaffar; Maitelo, Sultan Ahmed

2005-02-01

Pasteuria penetrans will build-up faster where there is a high initial nematode density and can suppress root-knot nematode populations in the roots of tomato plants. The effect of different initial densities of nematode (Meloidogyne javanica) (150, 750, 1500, 3000) and P. penetrans infected females (F1, F3) densities (F0=control and AC=absolute control without nematode or P. penetrans inoculum) on the build-up of Pasteuria population was investigated over four crop cycles. Two major points of interest were highlighted. First, that within a confined soil volume, densities of P. penetrans can increase >100 times within 2 or 3 crop cycles. Second, from a relatively small amount of spore inoculum, infection of the host is very high. There were more infected females in the higher P. penetrans doses. The root growth data confirms the greater number of females in the controls particularly at the higher inoculum densities in the third and fourth crops. P. penetrans generally caused the fresh root weights to be higher than those in the control. P. penetrans has shown greater reduction of egg masses per plant at most densities. The effects of different initial densities of M. javanica and P. penetrans on the development of the pest and parasite populations were monitored. And no attempt was made to return the P. penetrans spores to the pots after each crop so the build-up in actual numbers of infected females and spores under natural conditions may be underestimated.

Effect of the Entomogenous Nematode Nemplectana carpocapsae on the Tachinid Parasite Compsilura concinnata (Diptera: Tachinidae)

PubMed Central

Kaya, Harry K.

1984-01-01

The entomogenous nematode Neoaplectana carpocapsae and its associated bacterium, Xenorhabdus nematophilus, could not infect the pupal stage of the tachinid Compsilura concinnata through the puparium. N. carpocapsae had an adverse effect on 1-, 2- and 3-day-old C. concinnata larvae within the armyworm host in petri dish tests. All 1-day-old larvae treated with nematodes died in their hosts, whereas 61% and 69% of 2- and 3-day-old larvae treated with nematodes, respectively, died. However, the survivors developed to adults. Nine to thirty-seven percent of adult tachinids which emerged from nematode-treated soil (50 nematodes/cm²) were infected with N. carpocapsae. The nematode adversely affects C. concinnata directly by the frank infection of the tachinid and indirectly by causing the premature death of the host which results in tachinid death. PMID:19295866

On the track of transfer cell formation by specialized plant-parasitic nematodes.

PubMed

Rodiuc, Natalia; Vieira, Paulo; Banora, Mohamed Youssef; de Almeida Engler, Janice

2014-01-01

Transfer cells are ubiquitous plant cells that play an important role in plant development as well as in responses to biotic and abiotic stresses. They are highly specialized and differentiated cells playing a central role in the acquisition, distribution and exchange of nutrients. Their unique structural traits are characterized by augmented ingrowths of invaginated secondary wall material, unsheathed by an amplified area of plasma membrane enriched in a suite of solute transporters. Similar morphological features can be perceived in vascular root feeding cells induced by sedentary plant-parasitic nematodes, such as root-knot and cyst nematodes, in a wide range of plant hosts. Despite their close phylogenetic relationship, these obligatory biotrophic plant pathogens engage different approaches when reprogramming root cells into giant cells or syncytia, respectively. Both nematode feeding-cells types will serve as the main source of nutrients until the end of the nematode life cycle. In both cases, these nematodes are able to remarkably maneuver and reprogram plant host cells. In this review we will discuss the structure, function and formation of these specialized multinucleate cells that act as nutrient transfer cells accumulating and synthesizing components needed for survival and successful offspring of plant-parasitic nematodes. Plant cells with transfer-like functions are also a renowned subject of interest involving still poorly understood molecular and cellular transport processes.

Naturally acquired microchimerism

PubMed Central

Eikmans, Michael; van Halteren, Astrid GS; van Besien, Koen; van Rood, Jon J; Drabbels, Jos JM; Claas, Frans HJ

2014-01-01

Microchimerism represents a condition where one individual harbors genetically distinct cell populations, and the chimeric population constitutes <1% of the total number of cells. The most common natural source of microchimerism is pregnancy. The reciprocal cell exchange between a mother and her child often leads to the stable engraftment of hematopoietic and non-hematopoietic stem cells in both parties. Interaction between cells from the mother and those from the child may result in maternal immune cells becoming sensitized to inherited paternal alloantigens of the child, which are not expressed by the mother herself. Vice versa, immune cells of the child may become sensitized toward the non-inherited maternal alloantigens of the mother. The extent of microchimerism, its anatomical location, and the sensitivity of the techniques used for detecting its presence collectively determine whether microchimerism can be detected in an individual. In this review, we focus on the clinical consequences of microchimerism in solid organ and hematopoietic stem cell transplantation, and propose concepts derived from data of epidemiologic studies. Next, we elaborate on the latest molecular methodology, including digital PCR, for determining in a reliable and sensitive way the extent of microchimerism. For the first time, tools have become available to isolate viable chimeric cells from a host background, so that the challenges of establishing the biologic mechanisms and function of these cells may finally be tackled. PMID:24762743

Effects of midas® on nematodes in commercial floriculture production in Florida.

PubMed

Kokalis-Burelle, Nancy; Rosskopf, Erin N; Albano, Joseph P; Holzinger, John

2010-03-01

Cut flower producers currently have limited options for nematode control. Four field trials were conducted in 2006 and 2007 to evaluate Midas® (iodomethane:chloropicrin 50:50) for control of root-knot nematodes (Meloidogyne arenaria) on Celosia argentea var. cristata in a commercial floriculture production field in southeastern Florida. Midas (224 kg/ha) was compared to methyl bromide:chloropicrin (98:2, 224 kg/ha), and an untreated control. Treatments were evaluated for effects on Meloidogyne arenaria J2 and free-living nematodes in soil through each season, and roots at the end of each season. Plant growth and root disease were also assessed. Population levels of nematodes isolated from soil were highly variable in all trials early in the season, and generally rebounded by harvest, sometimes to higher levels in fumigant treatments than in the untreated control. Although population levels of nematodes in soil were not significantly reduced during the growing season, nematodes in roots and galling at the end of the season were consistently reduced with both methyl bromide and Midas compared to the untreated control. Symptoms of phytotoxicity were observed in Midas treatments during the first year and were attributed to Fe toxicity. Fertilization was adjusted during the second year to investigate potential fumigant/fertilizer interactions. Interactions occurred at the end of the fourth trial between methyl bromide and fertilizers with respect to root-knot nematode J2 isolated from roots and galling. Fewer J2 were isolated from roots treated with a higher level of Fe (3.05%) in the form of Fe sucrate, and galling was reduced in methyl bromide treated plots treated with this fertilizer compared to Fe EDTA. Reduced galling was also seen with Midas in Fe sucrate fertilized plots compared to Fe EDTA. This research demonstrates the difficulty of reducing high root-knot nematode population levels in soil in subtropical conditions in production fields that have been

Activated entomopathogenic nematode infective juveniles release lethal venom proteins

PubMed Central

Macchietto, Marissa; Baldwin, James; Mortazavi, Ali

2017-01-01

Entomopathogenic nematodes (EPNs) are unique parasites due to their symbiosis with entomopathogenic bacteria and their ability to kill insect hosts quickly after infection. It is widely believed that EPNs rely on their bacterial partners for killing hosts. Here we disproved this theory by demonstrating that the in vitro activated infective juveniles (IJs) of Steinernema carpocapsae (a well-studied EPN species) release venom proteins that are lethal to several insects including Drosophila melanogaster. We confirmed that the in vitro activation is a good approximation of the in vivo process by comparing the transcriptomes of individual in vitro and in vivo activated IJs. We further analyzed the transcriptomes of non-activated and activated IJs and revealed a dramatic shift in gene expression during IJ activation. We also analyzed the venom proteome using mass spectrometry. Among the 472 venom proteins, proteases and protease inhibitors are especially abundant, and toxin-related proteins such as Shk domain-containing proteins and fatty acid- and retinol-binding proteins are also detected, which are potential candidates for suppressing the host immune system. Many of the venom proteins have conserved orthologs in vertebrate-parasitic nematodes and are differentially expressed during IJ activation, suggesting conserved functions in nematode parasitism. In summary, our findings strongly support a new model that S. carpocapsae and likely other Steinernema EPNs have a more active role in contributing to the pathogenicity of the nematode-bacterium complex than simply relying on their symbiotic bacteria. Furthermore, we propose that EPNs are a good model system for investigating vertebrate- and human-parasitic nematodes, especially regarding the function of excretory/secretory products. PMID:28426766

The extent of wind-mediated dispersal of small metazoans, focusing nematodes.

PubMed

Ptatscheck, Christoph; Gansfort, Birgit; Traunspurger, Walter

2018-05-01

Wind-mediated transport is an important mechanism in the dispersal of small metazoans. Yet, concrete dispersal rates have hardly been examined. Here we present the results of an one-year field experiment investigating the composition and dispersal rates of aeroplankton. To gain insights into the dynamics of dispersal at the species level, we focused on nematodes, worldwide the most common metazoan taxon. Among the six taxa collected in this study (nematodes, rotifers, collembolans, tardigrades, mites, and thrips), nematodes had the highest dispersal rates (up to >3000 individuals m -2 in 4 weeks, 27 species identified) and represented >44% of aeroplankton. Only living nematodes, and no propagules, were dispersed. All taxa had a higher dispersal potential in environments linked to the source habitat, evidenced by the much higher deposition of organisms in funnels placed on the ground than on the rooftop of a ten-story building. Nematodes under conditions of high humidity and wind speed had the highest dispersal rates, while increasing temperatures and dryness had a significantly positive impact on the wind drift of mites and thrips. The results indicated that wind dispersal over long distances is possible. The notable organismal input by wind dispersal may contribute to biodiversity and ecosystem functions.

Metabarcoding analysis of strongylid nematode diversity in two sympatric primate species.

PubMed

Pafčo, Barbora; Čížková, Dagmar; Kreisinger, Jakub; Hasegawa, Hideo; Vallo, Peter; Shutt, Kathryn; Todd, Angelique; Petrželková, Klára J; Modrý, David

2018-04-12

Strongylid nematodes in large terrestrial herbivores such as great apes, equids, elephants, and humans tend to occur in complex communities. However, identification of all species within strongylid communities using traditional methods based on coproscopy or single nematode amplification and sequencing is virtually impossible. High-throughput sequencing (HTS) technologies provide opportunities to generate large amounts of sequence data and enable analyses of samples containing a mixture of DNA from multiple species/genotypes. We designed and tested an HTS approach for strain-level identification of gastrointestinal strongylids using ITS-2 metabarcoding at the MiSeq Illumina platform in samples from two free-ranging non-human primate species inhabiting the same environment, but differing significantly in their host traits and ecology. Although we observed overlapping of particular haplotypes, overall the studied primate species differed in their strongylid nematode community composition. Using HTS, we revealed hidden diversity in the strongylid nematode communities in non-human primates, more than one haplotype was found in more than 90% of samples and coinfections of more than one putative species occurred in 80% of samples. In conclusion, the HTS approach on strongylid nematodes, preferably using fecal samples, represents a time and cost-efficient way of studying strongylid communities and provides a resolution superior to traditional approaches.

Use of mixed cultures of biocontrol agents to control sheep nematodes.

PubMed

Baloyi, M A; Laing, M D; Yobo, K S

2012-03-23

Biological control is a promising non-chemical approach for the control of gastrointestinal nematodes of sheep. Use of combinations of biocontrol agents have been reported to be an effective method to increase the efficacy of biological control effects. In this study, combinations of either two Bacillus thuringiensis (Bt) or Clonostachys rosea (C. rosea) isolates and Bt+C. rosea isolates were evaluated in vitro in microtitre plates for their biocontrol activity on sheep nematodes. The Baermann technique was used to extract the surviving L3 larval stages of intestinal nematodes and counted under a dissecting microscope to determine the larval counts. Results indicate that there was a significant reduction of nematode counts due to combination of biocontrol agents (P<0.001). Combinations of Bt isolates reduced nematodes counts by 72.8%, 64% and 29.8%. The results revealed a control level of 57% when C. rosea isolates P3+P8 were combined. Combination of Bt and C. rosea isolates B10+P8 caused the greatest mortality of 76.7%. Most combinations were antagonistic, with only a few combinations showing an additive effect. None were synergistic. The isolate combinations were more effective than when isolates were used alone. Copyright © 2011 Elsevier B.V. All rights reserved.

Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes

PubMed Central

Courtot, Elise; Charvet, Claude L.; Beech, Robin N.; Harmache, Abdallah; Wolstenholme, Adrian J.; Holden-Dye, Lindy; O’Connor, Vincent; Peineau, Nicolas; Woods, Debra J.; Neveu, Cedric

2015-01-01

Acetylcholine receptors are pentameric ligand–gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. In nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. Despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. Interestingly, parasitic nematodes affecting human or animal health possess two closely related members of this gene family, acr-26 and acr-27 that are essentially absent in free-living or plant parasitic species. Using the pathogenic parasitic nematode of ruminants, Haemonchus contortus, as a model, we found that Hco-ACR-26 and Hco-ACR-27 are co-expressed in body muscle cells. We demonstrated that co-expression of Hco-ACR-26 and Hco-ACR-27 in Xenopus laevis oocytes led to the functional expression of an acetylcholine-receptor highly sensitive to the anthelmintics morantel and pyrantel. Importantly we also reported that ACR-26 and ACR-27, from the distantly related parasitic nematode of horses, Parascaris equorum, also formed a functional acetylcholine-receptor highly sensitive to these two drugs. In Caenorhabditis elegans, a free-living model nematode, we demonstrated that heterologous expression of the H. contortus and P. equorum receptors drastically increased its sensitivity to morantel and pyrantel, mirroring the pharmacological properties observed in Xenopus oocytes. Our results are the first to describe significant molecular determinants of a novel class of nematode body wall muscle AChR. PMID:26625142

The effects of repeated applications of the molluscicide metaldehyde and the biocontrol nematode Phasmarhabditis hermaphrodita on molluscs, earthworms, nematodes, acarids and collembolans: a two-year study in north-west Spain.

PubMed

Iglesias, Javier; Castillejo, José; Castro, Ramón

2003-11-01

Over two years, six consecutive field experiments were done in which the chemical molluscicide metaldehyde and the nematode biocontrol agent Phasmarhabditis hermaphrodita (Schneider) were applied at the standard field rates to replicated mini-plots successively planted with lettuce, Brussels sprouts, leaf beet and cabbage, to compare the effectiveness of different treatments in reducing slug damage to the crops. Soil samples from each plot were taken prior to the start of the experiments, and then monthly, to assess the populations of slugs, snails, earthworms, nematodes, acarids and collembolans. The experiments were done on the same site and each plot received the same treatment in the six experiments. The six treatments were: (1) untreated controls, (2) metaldehyde pellets, (3 and 4) nematodes applied to the planted area 3 days prior to planting without or with previous application of cow manure slurry, (5) nematodes applied to the area surrounding the planted area 3 days prior to planting, and (6) nematodes applied to the planted area once (only in the first of the six consecutive experiments). Only the metaldehyde treatment and the nematodes applied to the planted area at the beginning of each experiment without previous application of manure significantly reduced slug damage to the plants, and only metaldehyde reduced the number of slugs contaminating the harvested plants. The numbers of slugs, snails and earthworms in soil samples were compared among the six treatments tested: with respect to the untreated controls, the numbers of Deroceras reticulatum (Müller) were significantly affected only in the metaldehyde plots, and the numbers of Arion ater L only in the plots treated with nematodes applied to the planted area 3 days prior to planting without previous application of manure; numbers of snails (Ponentina ponentina (Morelet) and Oxychilus helveticus (Blum)) were not affected by the treatment. The total numbers of all earthworm species and of Lumbricus

Variation in the susceptibility of Drosophila to different entomopathogenic nematodes.

PubMed

Peña, Jennifer M; Carrillo, Mayra A; Hallem, Elissa A

2015-03-01

Entomopathogenic nematodes (EPNs) in the genera Heterorhabditis and Steinernema are lethal parasites of insects that are of interest as models for understanding parasite-host interactions and as biocontrol agents for insect pests. EPNs harbor a bacterial endosymbiont in their gut that assists in insect killing. EPNs are capable of infecting and killing a wide range of insects, yet how the nematodes and their bacterial endosymbionts interact with the insect immune system is poorly understood. Here, we develop a versatile model system for understanding the insect immune response to parasitic nematode infection that consists of seven species of EPNs as model parasites and five species of Drosophila fruit flies as model hosts. We show that the EPN Steinernema carpocapsae, which is widely used for insect control, is capable of infecting and killing D. melanogaster larvae. S. carpocapsae is associated with the bacterium Xenorhabdus nematophila, and we show that X. nematophila induces expression of a subset of antimicrobial peptide genes and suppresses the melanization response to the nematode. We further show that EPNs vary in their virulence toward D. melanogaster and that Drosophila species vary in their susceptibilities to EPN infection. Differences in virulence among different EPN-host combinations result from differences in both rates of infection and rates of postinfection survival. Our results establish a powerful model system for understanding mechanisms of host-parasite interactions and the insect immune response to parasitic nematode infection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Detection of antibodies to single-stranded DNA in naturally acquired and experimentally induced viral hepatitis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gust, I.D.; Feinstone, S.M.; Purcell, R.H.

1980-01-01

A sensitive ''Farr'' assay, utilizing /sup 125/I-labelled DNA was developed for detecting antibody to single-stranded DNA (anti-ssDNA). The test was shown to be specific and as sensitive as assays using /sup 14/C-labelled DNA, for the detection of antibody in patients with connective tissue diseases. Groups of sera from patients with naturally acquired viral hepatitis and experimentally infected chimpanzees were tested for anti-ssDNA by the /sup 125/I assay and by counterimmunoelectrophoresis (CIEP). No consistent pattern was observed with either technique, indicating the elevated levels of this antibody are not as reliable markers of parenchymal liver damage as had been previously suggested.

In vitro proteolysis of nematode FLPs by preparations from the free-living nematode Panagrellus redivivus and two plant-parasitic nematodes (Heterodera glycines and Meloidogyne incognita)

USDA-ARS?s Scientific Manuscript database

Proteolytic activities in extracts from three nematodes, the plant parasites Heterodera glycines and Meloidogyne incognita, and the free-living Panagrellus redivivus, were surveyed for substrate preferences using a battery of seven FRET-modified peptide substrates, all derived from members of the la...

Modelling nematode movement using time-fractional dynamics.

PubMed

Hapca, Simona; Crawford, John W; MacMillan, Keith; Wilson, Mike J; Young, Iain M

2007-09-07

We use a correlated random walk model in two dimensions to simulate the movement of the slug parasitic nematode Phasmarhabditis hermaphrodita in homogeneous environments. The model incorporates the observed statistical distributions of turning angle and speed derived from time-lapse studies of individual nematode trails. We identify strong temporal correlations between the turning angles and speed that preclude the case of a simple random walk in which successive steps are independent. These correlated random walks are appropriately modelled using an anomalous diffusion model, more precisely using a fractional sub-diffusion model for which the associated stochastic process is characterised by strong memory effects in the probability density function.

Understanding soil erosion impacts in temperate agroecosystems: bridging the gap between geomorphology and soil ecology using nematodes as a model organism

NASA Astrophysics Data System (ADS)

Baxter, C.; Rowan, J. S.; McKenzie, B. M.; Neilson, R.

2013-11-01

Soil is a key asset of natural capital, providing a myriad of goods and ecosystem services that sustain life through regulating, supporting and provisioning roles, delivered by chemical, physical and biological processes. One of the greatest threats to soil is accelerated erosion, which raises a natural process to unsustainable levels, and has downstream consequences (e.g.~economic, environmental and social). Global intensification of agroecosystems is a recognised major cause of soil erosion which, in light of predicted population growth and increased demand for food security, will continue or increase. Transport and redistribution of biota by soil erosion has hitherto been ignored and thus is poorly understood. With the move to sustainable intensification this is a key knowledge gap that needs to be addressed. Here we highlight the erosion-energy and effective-erosion-depth continuum in soils, differentiating between different forms of soil erosion, and argue that nematodes are an appropriate model taxa to investigate impacts of erosion on soil biota across scales. We review the different known mechanisms of soil erosion that impact on soil biota in general, and nematodes in particular, and highlight the few detailed studies, primarily from tropical regions, that have considered soil biota. Based on the limited literature and using nematodes as a model organism we outline future research priorities to initially address the important interrelationships between soil erosion processes and soil biota.

Divergent gene expression in the conserved dauer stage of the nematodes Pristionchus pacificus and Caenorhabditis elegans.

PubMed

Sinha, Amit; Sommer, Ralf J; Dieterich, Christoph

2012-06-19

An organism can respond to changing environmental conditions by adjusting gene regulation and by forming alternative phenotypes. In nematodes, these mechanisms are coupled because many species will form dauer larvae, a stress-resistant and non-aging developmental stage, when exposed to unfavorable environmental conditions, and execute gene expression programs that have been selected for the survival of the animal in the wild. These dauer larvae represent an environmentally induced, homologous developmental stage across many nematode species, sharing conserved morphological and physiological properties. Hence it can be expected that some core components of the associated transcriptional program would be conserved across species, while others might diverge over the course of evolution. However, transcriptional and metabolic analysis of dauer development has been largely restricted to Caenorhabditis elegans. Here, we use a transcriptomic approach to compare the dauer stage in the evolutionary model system Pristionchus pacificus with the dauer stage in C. elegans. We have employed Agilent microarrays, which represent 20,446 P. pacificus and 20,143 C. elegans genes to show an unexpected divergence in the expression profiles of these two nematodes in dauer and dauer exit samples. P. pacificus and C. elegans differ in the dynamics and function of genes that are differentially expressed. We find that only a small number of orthologous gene pairs show similar expression pattern in the dauers of the two species, while the non-orthologous fraction of genes is a major contributor to the active transcriptome in dauers. Interestingly, many of the genes acquired by horizontal gene transfer and orphan genes in P. pacificus, are differentially expressed suggesting that these genes are of evolutionary and functional importance. Our data set provides a catalog for future functional investigations and indicates novel insight into evolutionary mechanisms. We discuss the limited

Ancient horizontal transfers of retrotransposons between birds and ancestors of human pathogenic nematodes

PubMed Central

Suh, Alexander; Witt, Christopher C.; Menger, Juliana; Sadanandan, Keren R.; Podsiadlowski, Lars; Gerth, Michael; Weigert, Anne; McGuire, Jimmy A.; Mudge, Joann; Edwards, Scott V.; Rheindt, Frank E.

2016-01-01

Parasite host switches may trigger disease emergence, but prehistoric host ranges are often unknowable. Lymphatic filariasis and loiasis are major human diseases caused by the insect-borne filarial nematodes Brugia, Wuchereria and Loa. Here we show that the genomes of these nematodes and seven tropical bird lineages exclusively share a novel retrotransposon, AviRTE, resulting from horizontal transfer (HT). AviRTE subfamilies exhibit 83–99% nucleotide identity between genomes, and their phylogenetic distribution, paleobiogeography and invasion times suggest that HTs involved filarial nematodes. The HTs between bird and nematode genomes took place in two pantropical waves, >25–22 million years ago (Myr ago) involving the Brugia/Wuchereria lineage and >20–17 Myr ago involving the Loa lineage. Contrary to the expectation from the mammal-dominated host range of filarial nematodes, we hypothesize that these major human pathogens may have independently evolved from bird endoparasites that formerly infected the global breadth of avian biodiversity. PMID:27097561

Short-term effects of forest disturbances on soil nematode communities in European mountain spruce forests.

PubMed

Čerevková, A; Renčo, M; Cagáň, L

2013-09-01

The nematode communities in spruce forests were compared with the short-term effects of forest damage, caused by windstorm, wildfire and management practices of forest soils. Soil samples were collected in June and October from 2006 to 2008 in four different sites: (1) forest unaffected by the wind (REF); (2) storm-felled forest with salvaged timber (EXT); (3) modified forest affected by timber salvage (wood removal) and forest fire (FIR); and (4) storm-felled forest where timber had been left unsalvaged (NEX). Nematode analysis showed that the dominant species in all four investigated sites were Acrobeloides nanus and Eudorylaimus silvaticus. An increase of A. nanus (35% of the total nematode abundance) in the first year in the FIR site led to the highest total abundance of nematodes compared with other sites, where nematode abundance reached the same level in the third year. In the FIR site bacterial feeders appeared to be the most representative trophic group, although in the second and third year, after disturbance, the abundance of this trophic group gradually decreased. In the NEX site, the number of nematode species, population densities and Maturity Index were similar to that recorded for the FIR site. In EXT and NEX sites, the other dominant species was the plant parasitic nematode Paratylenchus microdorus. Analyses of nematodes extracted from different forest soil samples showed that the highest number of species and diversity index for species (H'spp) were in the REF site. Differences between the nematode fauna in REF and other localities were clearly depicted by cluster analysis. The greatest Structure Index and Enrichment Index values were also in REF. In the EXT site, the number of nematode species, their abundance, H'spp and Maturity Index were not significantly different from those recorded in the reference site.

Cellular Signaling Pathways and Posttranslational Modifications Mediated by Nematode Effector Proteins.

PubMed

Hewezi, Tarek

2015-10-01

Plant-parasitic cyst and root-knot nematodes synthesize and secrete a suite of effector proteins into infected host cells and tissues. These effectors are the major virulence determinants mediating the transformation of normal root cells into specialized feeding structures. Compelling evidence indicates that these effectors directly hijack or manipulate refined host physiological processes to promote the successful parasitism of host plants. Here, we provide an update on recent progress in elucidating the molecular functions of nematode effectors. In particular, we emphasize how nematode effectors modify plant cell wall structure, mimic the activity of host proteins, alter auxin signaling, and subvert defense signaling and immune responses. In addition, we discuss the emerging evidence suggesting that nematode effectors target and recruit various components of host posttranslational machinery in order to perturb the host signaling networks required for immunity and to regulate their own activity and subcellular localization. © 2015 American Society of Plant Biologists. All Rights Reserved.

Influence of the Sting Nematode, Belonolaimus longicaudalus, on Young Citrus Trees.

PubMed

Kaplan, D T

1985-10-01

The sting nematode, Belonolaimus longicaudatus, was associated with poor growth of citrus in a central Florida nursery. Foliage of trees was sparse and chlorotic. Affected rootstocks included Changsha and Cleopatra mandarin orange; Flying Dragon, Rubidoux, and Jacobsen trifoliate orange; Macrophylla and Milam lemon; Palestine sweet lime; sour orange; and the hybrids - Carrizo, Morton, and Rusk citrange and Swingle citrumelo. Root symptoms included apical swelling, development of swollen terminals containing 3-5 apical meristems and hyperplastic tissue, coarse roots, and a reduction in the number of fibrous roots. Population densities as high as 392 sting nematodes per liter soil were detected, with 80% of the population occurring in the top 30 cm of soil; however, nematodes were detected to 107 cm deep. Although an ectoparasite, the nematode was closely associated with citrus root systems and was transported with bare root nursery stock. Disinfestation was accomplished by hot water treatment (49 C for 5 minutes).

A soil microcosm to test the effects of pollutants on soil nematode and microarthropod communities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parmelee, R.W.; Wentsel, R.S.; Checkai, R.T.

1995-12-31

Previous studies have demonstrated that microcosms with field collected soil nematode and microarthropod communities are suitable model systems to detect effects of toxins on soil food web structure and function. The authors investigated the toxicity of copper, cadmium, malathion, and Aroclor 1254 to nematodes (total, bacterivores, fungivores, herbivores, omnivore-predators, hatchlings) and microarthropods (Prostigmata, Mesostigmata, Oribatida, Collembola, other arthropods). Nematodes were sensitive indicators of copper application, and total numbers were reduced at 100 {micro}g g{sup {minus}1}. Fungivore, bacterivore and omnivore-predators were the most susceptible trophic groups. Cadmium had no effects on either nematode or microarthropod communities. Microarthropods were more sensitive tomore » malathion than nematodes, and total microarthropod abundance was lower than controls at 320 {micro}g g{sup {minus}1}. Prostigmatid mites and other arthropods were the most affected groups. Only the herbivore nematode trophic group was affected by malathion, and numbers did not decline until 1,280 {micro}g g{sup {minus}1}. Aroclor 1254 also had a greater negative impact on microarthropods than on nematodes. Total microarthropod abundance declined at 2,500 {micro}g g{sup {minus}1}, while there was no effect on nematodes. Prostigmatid and oribatid mites were the most susceptible groups to PCB application. Strong differential sensitivity between nematode and microarthropod communities indicates that both groups need to be examined to fully evaluate the impact of chemicals on soil systems. The authors conclude that microcosms with field-collected communities of soil microfauna offer high resolution of the ecotoxicological effects of chemicals in complex soil systems.« less

Nematode parasites of fishes: recent advances and problems of their research.

PubMed

Moravec, F

2007-09-01

Although nematodes (Nematoda) belong to the most frequent and the most important parasites of fishes in the freshwater, brackish-water and marine environments throughout the world, the present knowledge of these parasites remains still incomplete, especially as to their biology and ecology, but also taxonomy, phylogeny, zoogeography, and the like. However, a certain progress in the research of fish nematodes has been achieved during recent years. An overview of some of the most important discoveries and results obtained is presented. As an example, existing problems in the taxonomy of these nematodes are shown in the dracunculoid family Philometridae (presently including 109 species in 9 genera), where they are associated mainly with some biological peculiarities of these mostly important tissue parasites. Nematodes of the Dracunculoidea as a whole remain poorly known; for example, of 139 valid species parasitizing fishes, 81 (58%) are known by females only and the males have not yet been described for members of 8 (27%) of genera. A taxonomic revision of this nematode group, based on detailed morphological, life history and molecular studies of individual species, is quite necessary; for the time being, Moravec (2006) has proposed a new classification system of dracunculoids, where, based on previous molecular studies, the Anguillicolidae is no longer listed in Dracunculoidea, but in an independent superfamily Anguillicoloidea. Important results have recently been achieved also in the taxonomy of fish nematodes belonging to other superfamilies, as well as in studies of their geographical distribution and diversity in different parts of the world and those of their biology. Opportunities for more detailed studies of fish nematodes have recently greatly improved with the use of some new methods, in particular SEM and DNA studies. There is a need to create a new classification system of these parasites reflecting phylogenetic relationships; a prerequisite for this is

SL2-like spliced leader RNAs in the basal nematode Prionchulus punctatus: New insight into the evolution of nematode SL2 RNAs.

PubMed

Harrison, Neale; Kalbfleisch, Andreas; Connolly, Bernadette; Pettitt, Jonathan; Müller, Berndt

2010-08-01

Spliced-leader (SL) trans-splicing has been found in all molecularly characterized nematode species to date, and it is likely to be a nematode synapomorphy. Most information regarding SL trans-splicing has come from the study of nematodes from a single monophyletic group, the Rhabditida, all of which employ SL RNAs that are identical to, or variants of, the SL1 RNA first characterized in Caenorhabditis elegans. In contrast, the more distantly related Trichinella spiralis, belonging to the subclass Dorylaimia, utilizes a distinct set of SL RNAs that display considerable sequence diversity. To investigate whether this is true of other members of the Dorylaimia, we have characterized SL RNAs from Prionchulus punctatus. Surprisingly, this revealed the presence of a set of SLs that show clear sequence similarity to the SL2 family of spliced leaders, which have previously only been found within the rhabditine group (which includes C. elegans). Expression of one of the P. punctatus SL RNAs in C. elegans reveals that it can compete specifically with the endogenous C. elegans SL2 spliced leaders, being spliced to the pre-mRNAs derived from downstream genes in operons, but does not compete with the SL1 spliced leaders. This discovery raises the possibility that SL2-like spliced leaders were present in the last common ancestor of the nematode phylum.

Management Options for Control of a Stunt and Needle Nematode in Southern Forest Nurseries

Treesearch

Michelle M. Cram; Stephen W. Fraedrich

2005-01-01

Crop rotation and fallow are management options that can be used to control plant parasitic nematodes in forest tree nurseries. Before these options can be put into practice, it is important to determine the host range and survivability under fallow of the parasitic nematode to be controlled. The results of host range tests on a needle nematode (Longidorus...

Low cost production of nematodes for biological control of insect pests

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes are produced in two ways: in artificial media using liquid or solid fermentation methods (in vitro) or by mass producing insect hosts to be artificially exposed to mass infection by nematodes (in vivo). The yellow mealworm (Tenebrio molitor) is a good host for in vivo nema...

Nematodes as bioindicators of ecosystem recovery during phytoremediation of crude oil contaminated soil.

PubMed

Savin, Mary C; Wolf, Duane C; Davis, K Jody; Gbur, Edward E; Thoma, Greg J

2015-01-01

Restoration of a weathered crude oil contaminated site undergoing phytoremediation was evaluated using nematodes as bioindicators. Samples were collected twice per year equating to spring and fall/winter. Mean annual total abundances ranged from 18-130 in the non-fertilized non-vegetated control (CTR) to 69-728 in tall fescue-ryegrass (FES) to 147-749 (100 g(-1)) in the fertilized bermudagrass-fescue (BER) treatment. Proportions of plant-parasitic (PP) and free-living (FL) nematodes were significantly impacted by treatment, but not year, with PP nematodes accounting for 27, 59, and 68% of CTR, FES, and BER communities, respectively. There was no significant year by season by treatment or treatment by year effect for total, PP, or FL nematode abundances. Diversity did not increase over time. The BER and FES treatments had more mature communities as indicated by higher plant-parasitic index (PPI) values. Phytoremediation accelerates petroleum degradation and alters the soil habitat which is reflected in the nematode community. However, low numbers and inconsistent presence of persister strategist omnivores and predators, and the lack in improvement over time in treatment effects for total and PP nematode abundances, PP and FL proportions, or PPI indicate the system is being rehabilitated but has not been restored after 69 months of phytoremediation.

Spatial distribution of nematodes in soil cultivated with sugarcane under different uses

NASA Astrophysics Data System (ADS)

Cardoso, M. O.; Pedrosa, E. M. R.; Vicente, T. F. S.; Siqueira, G. M.; Montenegro, A. A. A.

2012-04-01

Sugarcane is a crop of major importance within the Brazilian economy, being an activity that generates energy and with high capacity to develop various economic sectors. Currently the greatest challenge is to maximize productivity and minimize environmental impacts. The plant-parasites nematodes have great expression, because influence directly the productive potential of sugarcane crops. Accordingly, little research has been devoted to the study of spatial variability of nematodes. Thus, the purpose of this work is to analyze the spatial distribution of nematodes in a soil cultivated with sugarcane in areas with and without irrigation, with distinct spacing of sampling to determine the differences between the sampling scales. The study area is located in the municipality of Goiana (Pernambuco State, Brazil). The experiment was conducted in two areas with 40 hectares each, being collected 90 samples at different spacing: 18 samples with spacing of 200.00 x 200.00 m, 36 samples with spacing of 20.00 m x 20.00 m and 36 samples with spacing of 2.00 m x 2.00 m. Soil samples were collected at deep of 0.00-0.20 m and nematodes were extracted per 300 cm3 of soil through centrifugal flotation in sucrose being quantified, classified according trophic habit (plant-parasites, fungivores, bacterivores, omnivores and predators) and identified in level of genus or family. In irrigated area the amount of water applied was determined considering the evapotranspiration of culture. The data were analyzed using classical statistics and geostatistics. The results demonstrated that the data showed high values of coefficient of variation in both study areas. All attributes studied showed log normal frequency distribution. The area B (irrigated) has a population of nematodes more stable than the area A (non-irrigated), a fact confirmed by its mean value of the total population of nematodes (282.45 individuals). The use of geostatistics not allowed to assess the spatial distribution of

Travelling at a slug's pace: possible invertebrate vectors of Caenorhabditis nematodes.

PubMed

Petersen, Carola; Hermann, Ruben Joseph; Barg, Mike-Christoph; Schalkowski, Rebecca; Dirksen, Philipp; Barbosa, Camilo; Schulenburg, Hinrich

2015-07-13

How do very small animals with limited long-distance dispersal abilities move between locations, especially if they prefer ephemeral micro-habitats that are only available for short periods of time? The free-living model nematode Caenorhabditis elegans and several congeneric taxa appear to be common in such short-lived environments, for example decomposing fruits or other rotting plant material. Dispersal is usually assumed to depend on animal vectors, yet all current data is based on only a limited number of studies. In our project we performed three comprehensive field surveys on possible invertebrate vectors in North German locations containing populations of C. elegans and two related species, especially C. remanei, and combined these screens with an experimental analysis of persistence in one of the vector taxa. Our field survey revealed that Caenorhabditis nematodes are commonly found in slugs, isopods, and chilopods, but are not present in the remaining taxonomic groups examined. Surprisingly, the nematodes were frequently isolated from the intestines of slugs, even if slugs were not collected in close association with suitable substrates for Caenorhabditis proliferation. This suggests that the nematodes are able to enter the slug intestines and persist for certain periods of time. Our experimental analysis confirmed the ability of C. elegans to invade slug intestines and subsequently be excreted alive with the slug feces, although only for short time periods under laboratory conditions. We conclude that three invertebrate taxonomic groups represent potential vectors of Caenorhabditis nematodes. The nematodes appear to have evolved specific adaptations to enter and persist in the harsh environment of slug intestines, possibly indicating first steps towards a parasitic life-style.

Genomic mechanisms accounting for the adaptation to parasitism in nematode-trapping fungi.

PubMed

Meerupati, Tejashwari; Andersson, Karl-Magnus; Friman, Eva; Kumar, Dharmendra; Tunlid, Anders; Ahrén, Dag

2013-11-01

Orbiliomycetes is one of the earliest diverging branches of the filamentous ascomycetes. The class contains nematode-trapping fungi that form unique infection structures, called traps, to capture and kill free-living nematodes. The traps have evolved differently along several lineages and include adhesive traps (knobs, nets or branches) and constricting rings. We show, by genome sequencing of the knob-forming species Monacrosporium haptotylum and comparison with the net-forming species Arthrobotrys oligospora, that two genomic mechanisms are likely to have been important for the adaptation to parasitism in these fungi. Firstly, the expansion of protein domain families and the large number of species-specific genes indicated that gene duplication followed by functional diversification had a major role in the evolution of the nematode-trapping fungi. Gene expression indicated that many of these genes are important for pathogenicity. Secondly, gene expression of orthologs between the two fungi during infection indicated that differential regulation was an important mechanism for the evolution of parasitism in nematode-trapping fungi. Many of the highly expressed and highly upregulated M. haptotylum transcripts during the early stages of nematode infection were species-specific and encoded small secreted proteins (SSPs) that were affected by repeat-induced point mutations (RIP). An active RIP mechanism was revealed by lack of repeats, dinucleotide bias in repeats and genes, low proportion of recent gene duplicates, and reduction of recent gene family expansions. The high expression and rapid divergence of SSPs indicate a striking similarity in the infection mechanisms of nematode-trapping fungi and plant and insect pathogens from the crown groups of the filamentous ascomycetes (Pezizomycotina). The patterns of gene family expansions in the nematode-trapping fungi were more similar to plant pathogens than to insect and animal pathogens. The observation of RIP activity

Genomic Mechanisms Accounting for the Adaptation to Parasitism in Nematode-Trapping Fungi

PubMed Central

Meerupati, Tejashwari; Andersson, Karl-Magnus; Friman, Eva; Kumar, Dharmendra; Tunlid, Anders; Ahrén, Dag

2013-01-01

Orbiliomycetes is one of the earliest diverging branches of the filamentous ascomycetes. The class contains nematode-trapping fungi that form unique infection structures, called traps, to capture and kill free-living nematodes. The traps have evolved differently along several lineages and include adhesive traps (knobs, nets or branches) and constricting rings. We show, by genome sequencing of the knob-forming species Monacrosporium haptotylum and comparison with the net-forming species Arthrobotrys oligospora, that two genomic mechanisms are likely to have been important for the adaptation to parasitism in these fungi. Firstly, the expansion of protein domain families and the large number of species-specific genes indicated that gene duplication followed by functional diversification had a major role in the evolution of the nematode-trapping fungi. Gene expression indicated that many of these genes are important for pathogenicity. Secondly, gene expression of orthologs between the two fungi during infection indicated that differential regulation was an important mechanism for the evolution of parasitism in nematode-trapping fungi. Many of the highly expressed and highly upregulated M. haptotylum transcripts during the early stages of nematode infection were species-specific and encoded small secreted proteins (SSPs) that were affected by repeat-induced point mutations (RIP). An active RIP mechanism was revealed by lack of repeats, dinucleotide bias in repeats and genes, low proportion of recent gene duplicates, and reduction of recent gene family expansions. The high expression and rapid divergence of SSPs indicate a striking similarity in the infection mechanisms of nematode-trapping fungi and plant and insect pathogens from the crown groups of the filamentous ascomycetes (Pezizomycotina). The patterns of gene family expansions in the nematode-trapping fungi were more similar to plant pathogens than to insect and animal pathogens. The observation of RIP activity

Influence of four nematodes on root and shoot growth parameters in grape.

PubMed

Anwar, S A; Van Gundy, S D

1989-04-01

Two grape cultivars, susceptible French Colombard and tolerant Rubired, and four nematodes, Meloidogyne incognita, Pratylenchus vulnus, Tylenchulus semipenetrans, and Xiphinema index, were used to quantify the equilibrium between root (R) and shoot (S) growth. Root and shoot growth of French Colombard was retarded by M. incognita, P. vulnus, and X. index but not by T. semipenetrans. Although the root growth of Rubired was limited by all the nematodes, the shoot growth was limited only by X. index. The R:S ratios of Rubired were higher than those of French Colombard. The reduced R:S ratios of Rubired were primarily an expression of reduction in root systems without an equal reduction in shoot growth, whereas in French Colombard the reduced R:S ratios were due to a reduction in both shoot growth and root growth and to a greater reduction in root growth than shoot growth. All nematodes reproduced equally well on both cultivars. Both foliage and root growth of French Colombard were significantly reduced by M. incognita and P. vulnus. Nematodes reduced the shoot length by reducing the internode length. Accumulative R:S ratios in inoculated plants were significantly smaller than those in controls in all nematode treatments but not at individual harvest dates. Bud break was delayed by X. index and was initiated earlier by P. vulnus and M. incognita. All buds in nematode treatments were less vigorous than in controls.

First Report of the new root-lesion nematode Pratylenchus sp. on soybean in North Dakota

USDA-ARS?s Scientific Manuscript database

Root-lesion nematodes (Pratylenchus spp.) are important nematode pests on soybean. In 2015, two soil samples were collected from a soybean field in Richland County, ND. Nematodes were extracted from soil using a sugar centrifugal flotation method, revealing these two samples contained 125 and 350 ro...

Trematodes enhance the development of the nematode-trapping fungus Arthrobotrys (Duddingtonia) flagrans.

PubMed

Arias, María Sol; Suárez, José; Cazapal-Monteiro, Cristiana Filipa; Francisco, Iván; López-Arellano, María Eugenia; Piñeiro, Pablo; Suárez, José Luis; Sánchez-Andrade, Rita; Mendoza de Gives, Pedro; Paz-Silva, Adolfo

2013-01-01

The capability of helminth (nematode and trematode) parasites in stimulating nematode trap and chlamydospore development of the nematophagous fungus Arthrobotrys (formerly Duddingtonia) flagrans was explored. Dead adult specimens of trematodes (the liver fluke Fasciola hepatica and the rumen fluke Calicophoron daubneyi) and nematodes (the ascarid Parascaris equorum and the strongylid Oesophagostomum spp.), as well as their secretory products, were placed onto corn meal agar plates concurrently inoculated with A. flagrans. Trapping organs were observed after 5 d and chlamydospores after 16 d, including in the control plates in the absence of parasitic stimulus. However, our data shows that both nematodes and trematodes increase trap and chlamydospore production compared with controls. We show for the first time that significantly higher numbers of traps and chlamydospores were observed in the cultures coinoculated with adult trematodes. We conclude that both the traps and chlamydospores formation are not only related to nematode-specific stimuli. The addition of secretory products of the trematode C. daubneyi to culture medium has potential for use in the large scale production of chlamydospores. Copyright © 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

The Transcriptome of Nacobbus aberrans Reveals Insights into the Evolution of Sedentary Endoparasitism in Plant-Parasitic Nematodes

PubMed Central

Eves-van den Akker, Sebastian; Lilley, Catherine J.; Danchin, Etienne G. J.; Rancurel, Corinne; Cock, Peter J. A.; Urwin, Peter E.; Jones, John T.

2014-01-01

Within the phylum Nematoda, plant-parasitism is hypothesized to have arisen independently on at least four occasions. The most economically damaging plant-parasitic nematode species, and consequently the most widely studied, are those that feed as they migrate destructively through host roots causing necrotic lesions (migratory endoparasites) and those that modify host root tissue to create a nutrient sink from which they feed (sedentary endoparasites). The false root-knot nematode Nacobbus aberrans is the only known species to have both migratory endoparasitic and sedentary endoparasitic stages within its life cycle. Moreover, its sedentary stage appears to have characteristics of both the root-knot and the cyst nematodes. We present the first large-scale genetic resource of any false-root knot nematode species. We use RNAseq to describe relative abundance changes in all expressed genes across the life cycle to provide interesting insights into the biology of this nematode as it transitions between modes of parasitism. A multigene phylogenetic analysis of N. aberrans with respect to plant-parasitic nematodes of all groups confirms its proximity to both cyst and root-knot nematodes. We present a transcriptome-wide analysis of both lateral gene transfer events and the effector complement. Comparing parasitism genes of typical root-knot and cyst nematodes to those of N. aberrans has revealed interesting similarities. Importantly, genes that were believed to be either cyst nematode, or root-knot nematode, “specific” have both been identified in N. aberrans. Our results provide insights into the characteristics of a common ancestor and the evolution of sedentary endoparasitism of plants by nematodes. PMID:25123114

Parasitism genes and host range disparities in biotrophic nematodes: the conundrum of polyphagy versus specialisation.

PubMed

Blok, Vivian C; Jones, John T; Phillips, Mark S; Trudgill, David L

2008-03-01

This essay considers biotrophic cyst and root-knot nematodes in relation to their biology, host-parasite interactions and molecular genetics. These nematodes have to face the biological consequences of the physical constraints imposed by the soil environment in which they live while their hosts inhabit both above and below ground environments. The two groups of nematodes appear to have adopted radically different solutions to these problems with the result that one group is a host specialist and reproduces sexually while the other has an enormous host range and reproduces by mitotic parthenogenesis. We consider what is known about the modes of parasitism used by these nematodes and how it relates to their host range, including the surprising finding that parasitism genes in both nematode groups have been recruited from bacteria. The nuclear and mitochondrial genomes of these two nematode groups are very different and we consider how these findings relate to the biology of the organisms.

Development of a nematode offspring counting assay for rapid and simple soil toxicity assessment.

PubMed

Kim, Shin Woong; Moon, Jongmin; Jeong, Seung-Woo; An, Youn-Joo

2018-05-01

Since the introduction of standardized nematode toxicity assays by the American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO), many studies have reported their use. Given that the currently used standardized nematode toxicity assays have certain limitations, in this study, we examined the use of a novel nematode offspring counting assay for evaluating soil ecotoxicity based on a previous soil-agar isolation method used to recover live adult nematodes. In this new assay, adult Caenorhabditis elegans were exposed to soil using a standardized toxicity assay procedure, and the resulting offspring in test soils attracted by a microbial food source in agar plates were counted. This method differs from previously used assays in terms of its endpoint, namely, the number of nematode offspring. The applicability of the bioassay was demonstrated using metal-spiked soils, which revealed metal concentration-dependent responses, and with 36 field soil samples characterized by different physicochemical properties and containing various metals. Principal component analysis revealed that texture fraction (clay, sand, and silt) and electrical conductivity values were the main factors influencing the nematode offspring counting assay, and these findings warrant further investigation. The nematode offspring counting assay is a rapid and simple process that can provide multi-directional toxicity assessment when used in conjunction with other standard methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Pathogenicity of Two Species of Entomopathogenic Nematodes Against the Greenhouse Whitefly, Trialeurodes vaporariorum (Hemiptera: Aleyrodidae), in Laboratory and Greenhouse Experiments.

PubMed

Rezaei, Nastaran; Karimi, Javad; Hosseini, Mojtaba; Goldani, Morteza; Campos-Herrera, Raquel

2015-03-01

The greenhouse whitefly Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) is a polyphagous pest in greenhouse crops. The efficacy of two entomopathogenic nematodes (EPN), Steinernema feltiae and Heterorhabditis bacteriophora, as biological control agents against T. vaporariorum was evaluated using two model crops typical of vegetable greenhouse productions: cucumber and pepper. Laboratory tests evaluated adults and second nymphal instars for pest susceptibility to different EPN species at different concentrations of infective juveniles (IJ; 0, 25, 50, 100, 150, 200, and 250 IJ per cm(2)); subsequent greenhouse trials against second nymphal instars on cucumber and pepper plants evaluated more natural conditions. Concentrations were applied in combination with Triton X-100 (0.1% v/v), an adjuvant for increasing nematode activity. In laboratory studies, both life stages were susceptible to infection by the two nematode species, but S. feltiae recorded a lower LC50 than H. bacteriophora for both insect stages. Similarly, in greenhouse experiments, S. feltiae required lower concentrations of IJ than H. bacteriophora to reach the same mortality in nymphs. In greenhouse trials, a significant difference was observed in the triple interaction among nematode species × concentration × plant. Furthermore, the highest mortality rate of the second nymphal instars of the T. vaporariorum was obtained from the application of S. feltiae concentrated to 250 IJ/cm(2) on cucumber (49 ± 1.23%). The general mortality caused by nematodes was significantly higher in cucumber than in pepper. These promising results support further investigation for the optimization of the best EPN species/concentration in combination with insecticides or adjuvants to reach a profitable control of this greenhouse pest.

Insights into Adaptations to a Near-Obligate Nematode Endoparasitic Lifestyle from the Finished Genome of Drechmeria coniospora

PubMed Central

Zhang, Liwen; Zhou, Zhengfu; Guo, Qiannan; Fokkens, Like; Miskei, Márton; Pócsi, István; Zhang, Wei; Chen, Ming; Wang, Lei; Sun, Yamin; Donzelli, Bruno G. G.; Gibson, Donna M.; Nelson, David R.; Luo, Jian-Guang; Rep, Martijn; Liu, Hang; Yang, Shengnan; Wang, Jing; Krasnoff, Stuart B.; Xu, Yuquan; Molnár, István; Lin, Min

2016-01-01

Nematophagous fungi employ three distinct predatory strategies: nematode trapping, parasitism of females and eggs, and endoparasitism. While endoparasites play key roles in controlling nematode populations in nature, their application for integrated pest management is hindered by the limited understanding of their biology. We present a comparative analysis of a high quality finished genome assembly of Drechmeria coniospora, a model endoparasitic nematophagous fungus, integrated with a transcriptomic study. Adaptation of D. coniospora to its almost completely obligate endoparasitic lifestyle led to the simplification of many orthologous gene families involved in the saprophytic trophic mode, while maintaining orthologs of most known fungal pathogen-host interaction proteins, stress response circuits and putative effectors of the small secreted protein type. The need to adhere to and penetrate the host cuticle led to a selective radiation of surface proteins and hydrolytic enzymes. Although the endoparasite has a simplified secondary metabolome, it produces a novel peptaibiotic family that shows antibacterial, antifungal and nematicidal activities. Our analyses emphasize the basic malleability of the D. coniospora genome: loss of genes advantageous for the saprophytic lifestyle; modulation of elements that its cohort species utilize for entomopathogenesis; and expansion of protein families necessary for the nematode endoparasitic lifestyle. PMID:26975455

Interactive effects of elevated ozone and UV-B radiation on soil nematode diversity.

PubMed

Bao, Xuelian; Li, Qi; Hua, Jianfeng; Zhao, Tianhong; Liang, Wenju

2014-01-01

Ultraviolet-B (UV-B) radiation and elevated tropospheric ozone may cause reductions in the productivity and quality of important agricultural crops. However, research regarding their interactive effect is still scarce, especially on the belowground processes. Using the open top chambers experimental setup, we monitored the response of soil nematodes to the elevated O3 and UV-B radiation individually as well as in combination. Our results indicated that elevated O3 and UV-B radiation have impact not only on the belowground biomass of plants, but also on the community structure and functional diversity of soil nematodes. The canonical correspondence analysis suggested that soil pH, shoot biomass and microbial biomass C and N were relevant parameters that influencing soil nematode distribution. The interactive effects of elevated O3 and UV-B radiation was only observed on the abundance of bacterivores. UV-B radiation significantly increased the abundance of total nematodes and bacterivores in comparison with the control at pod-filling stage of soybean. Following elevated O3, nematode diversity index decreased and dominance index increased relative to the control at pod-filling stage of soybean. Nematode functional diversity showed response to the effects of elevated O3 and UV-B radiation at pod-bearing stage. Higher enrichment index and lower structure index in the treatment with both elevated O3 and UV-B radiation indicated a stressed soil condition and degraded soil food web. However, the ratios of nematode trophic groups suggested that the negative effects of elevated O3 on soil food web may be weakened by the UV-B radiations.

Association between entomopathogenic nematodes and fungi for control of Rhipicephalus microplus (Acari: Ixodidae).

PubMed

Monteiro, Caio Márcio Oliveira; Araújo, Laryssa Xavier; Matos, Renata Silva; da Silva Golo, Patrícia; Angelo, Isabele Costa; de Souza Perinotto, Wendell Marcelo; Coelho Rodrigues, Camila Aparecida; Furlong, John; Bittencourt, Vânia Rita Elias Pinheiro; Prata, Márcia Cristina Azevedo

2013-10-01

The aim of the study was to assess the effect of the association of entomopathogenic nematodes and fungi on Rhipicephalus microplus. The nematodes used were Heterorhabditis bacteriophora HP88 and Heterorhabditis indica LPP1 and the fungi were Metarhizium anisopliae IBCB 116 and Beauveria bassiana ESALQ 986. In the groups treated with the fungi, the females were immersed for 3 min in a conidial suspension, while in the groups treated with the nematodes, the ticks were exposed to infective juveniles. To evaluate the interaction between entomopathogens, the females were first immersed in a conidial suspension and then exposed to the nematodes. The egg mass weight and hatching percentage values of the groups treated with M. anisopliae IBCB 116 and B. bassiana ESALQ 986 in the two experiments were statistically similar (p > 0.05) to the values of the control group. In the groups treated only with nematodes, there was a significant reduction (p < 0.05) in the egg mass weight, a fact also observed for the hatching percentage of the group treated with H. indica LPP1. In all the groups treated with nematodes in association with fungi, there was a significant reduction (p < 0.05) in the egg mass weight and hatching percentage. The percentage of control of the groups treated with fungi alone varied from 31 to 55%. In the groups treated with nematodes associated or not with fungi, the control percentage was always greater than 90% and reached 100% in the group treated with H. bacteriophora HP88 associated with the fungus M. anisopliae IBCB 116.

Risk of Newly Detected Infections and Cervical Abnormalities in Women Seropositive for Naturally Acquired Human Papillomavirus Type 16/18 Antibodies: Analysis of the Control Arm of PATRICIA

PubMed Central

Castellsagué, Xavier; Naud, Paulo; Chow, Song-Nan; Wheeler, Cosette M.; Germar, Maria Julieta V.; Lehtinen, Matti; Paavonen, Jorma; Jaisamrarn, Unnop; Garland, Suzanne M.; Salmerón, Jorge; Apter, Dan; Kitchener, Henry; Teixeira, Julio C.; Skinner, S. Rachel; Limson, Genara; Szarewski, Anne; Romanowski, Barbara; Aoki, Fred Y.; Schwarz, Tino F.; Poppe, Willy A. J.; Bosch, F. Xavier; de Carvalho, Newton S.; Peters, Klaus; Tjalma, Wiebren A. A.; Safaeian, Mahboobeh; Raillard, Alice; Descamps, Dominique; Struyf, Frank; Dubin, Gary; Rosillon, Dominique; Baril, Laurence

2014-01-01

Background. We examined risk of newly detected human papillomavirus (HPV) infection and cervical abnormalities in relation to HPV type 16/18 antibody levels at enrollment in PATRICIA (Papilloma Trial Against Cancer in Young Adults; NCT00122681). Methods. Using Poisson regression, we compared risk of newly detected infection and cervical abnormalities associated with HPV-16/18 between seronegative vs seropositive women (15–25 years) in the control arm (DNA negative at baseline for the corresponding HPV type [HPV-16: n = 8193; HPV-18: n = 8463]). Results. High titers of naturally acquired HPV-16 antibodies and/or linear trend for increasing antibody levels were significantly associated with lower risk of incident and persistent infection, atypical squamous cells of undetermined significance or greater (ASCUS+), and cervical intraepithelial neoplasia grades 1/2 or greater (CIN1+, CIN2+). For HPV-18, although seropositivity was associated with lower risk of ASCUS+ and CIN1+, no association between naturally acquired antibodies and infection was demonstrated. Naturally acquired HPV-16 antibody levels of 371 (95% confidence interval [CI], 242–794), 204 (95% CI, 129–480), and 480 (95% CI, 250–5756) EU/mL were associated with 90% reduction of incident infection, 6-month persistent infection, and ASCUS+, respectively. Conclusions. Naturally acquired antibodies to HPV-16, and to a lesser extent HPV-18, are associated with some reduced risk of subsequent infection and cervical abnormalities associated with the same HPV type. PMID:24610876